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Research Article
Revision of the ant genus Melophorus (Hymenoptera, Formicidae)
expand article infoBrian E. Heterick§, Mark Castalanelli|, Steve O. Shattuck
‡ Curtin University, Perth, Australia
§ Western Australian Museum, Welshpool, Australia
| EcoDiagnostics Pty Ltd, Welshpool, Australia
¶ CSIRO Entomology, Canberra, Australia
Open Access

Abstract

The fauna of the purely Australian formicine ant genus Melophorus (Hymenoptera: Formicidae) is revised. This project involved integrated morphological and molecular taxonomy using one mitochondrial gene (COI) and four nuclear genes (AA, H3, LR and Wg). Seven major clades were identified and are here designated as the M. aeneovirens, M. anderseni, M. biroi, M. fulvihirtus, M. ludius, M. majeri and M. potteri species-groups. Within these clades, smaller complexes of similar species were also identified and designated species-complexes. The M. ludius species-group was identified purely on molecular grounds, as the morphology of its members is indistinguishable from typical members of the M. biroi species-complex within the M. biroi species-group. Most species-complexes sampled were also found to be monophyletic. Sequencing generally supported monophyly in taxa sampled but some species of the M. fieldi complex and M. biroi were not monophyletic and the implications arising from this are discussed in this monograph. Based on morphology, ninety-three species are recognized, 73 described as new. A further new species (here called 'Species K' [TERC Collection]) is noted in the taxonomic list, but is not described in this work. One species is removed from Melophorus: M. scipio Forel is here placed provisionally in Prolasius. Six species and five subspecies pass into synonymy. Of the full species, M. constans Santschi, M. iridescens (Emery) and M. insularis Wheeler are synonymized under M. aeneovirens (Lowne), M. pillipes Santschi is synonymized under M. turneri Forel, M. marius Forel is synonymized under M. biroi Forel, and M. omniparens Forel is synonymized under M. wheeleri Forel. Of the subspecies, M. iridescens fraudatrix and M. iridescens froggatti Forel are synonymized under M. aeneovirens (Lowne), M. turneri aesopus Forel and M. turneri candidus Santschi are synonymized under M. turneri Forel and M. fieldi propinqua Viehmeyer is synonymized under M. biroi. Camponotus cowlei Froggatt is reinstated as a junior synonym of Melophorus bagoti Lubbock. In addition, the subspecies M. fieldi major Forel, M. ludius sulla Forel and M. turneri perthensis Forel are raised to species. A key to workers of the genus is supplied. A lectotype is designated for M. curtus Forel, M. sulla, and M. turneri.

Keywords

Hymenoptera , Formicidae , Formicinae , Melophorus , taxonomy, new species, Australia.

Introduction

Melophorus is an easily characterized member of the ant subfamily Formicinae. This genus shares with all formicines the possession of an acidipore (a tubular structure that disseminates formic acid against enemies). The genus Melophorus is entirely restricted to Australia, and all known members are thermophilic or believed to be predominantly so, mainly being terrestrial foragers. The very many species of Melophorus are particularly abundant in hot, arid or semi-arid environments where they are diurnally active, mostly in the summer months. Arguably, Melophorus is one of the most poorly understood large ant genera in the world. Just a fraction of the constituent species has been described to the present time, the group has never been monographed, and synonymy is prevalent among the 32 taxa that have received names. Here we provide the first comprehensive monograph of the genus. Because this group is so little known, the likely total number of species has been regarded as problematic. Figures as high as 1000 species (Andersen 2007) have been suggested, but this monograph indicates the real figure is around one tenth of that.

Taxonomic history. The genus Melophorus was originally erected for the single species Melophorus bagoti (Lubbock 1883). However, a species described earlier in the genus Formica was later revealed to be a Melophorus (M. aeneovirens [Lowne 1865]). Lubbock’s diagnosis of the genus was poor and initially Melophorus lacked any real systematic framework. As a result, Melophorus was initially very broadly defined and accumulated species, including non-Australian species, that are now placed in other genera.

Forel (1911) had already commented on the diverse morphology of Melophorus that caused many of the then known species to be confused with unrelated genera or extralimital genera (i.e. those occurring outside of Australia). However, based on the appearance of the proventriculus, he affirmed their basic unity at the generic level. In 1912, he made a more determined effort to formally link the overly broad ‘Melophorus’ with taxa that seemed to him to share significant apomorphies (Forel 1912). In this work, ‘Melophorus’ was placed in a subfamily titled Camponotinae (originally erected by Forel in 1878 as ‘Camponotidae’ and later [1893] corrected by him). Forel divided the Camponotinae into three assemblages of taxa, based principally on the proventriculus. He also provided all-caste keys to the formicine genera known at the time. ‘Melophorus’ found a home in the second assemblage, the so-called Mesocamponotinae, and in a tribe, Melophorini, that consisted of Melophorus and another Australian genus, Notoncus. These two genera were distinguished from other formicines by their 12-segmented antennae and (with the exception of the ‘Australian Melophorus’!) the presence of a discoidal cell in the wing of the sexuals.

Within the first two decades of the twentieth century most of the species wrongly placed in Melophorus were correctly reassigned by Forel and another great myrmecologist of his era, Carlo Emery. Similarly, species such as M. aeneovirens were incorporated into Melophorus. Wheeler (1920) replaced the old subfamily name Camponotinae with Formicinae, based on his work on larval characters, and established the foundations of a subfamily classification that remained substantially unchanged (with just a few additions) until the modern era of molecular systematics.

By 1922, the taxonomic status of Melophorus as a well-defined genus in its own right was gradually starting to emerge, although in that year Carlo Emery still subsumed genuine Melophorus species (along with several Prolasius species and Notoncus spinisquamis André) under a subgenus ‘Melophorus’ (Emery 1922). ‘Prolasius’ and ‘Lasiophanes’ constituted the remaining two subgenera under the broader umbrella genus Melophorus. Interestingly, Notoncus was treated by Emery as a discrete, though closely related genus. In Emery’s treatment, all non-Australian taxa had now been removed from the subgenus ‘Melophorus’, although of the diagnostic characters that Emery listed for workers of the subgenus, only polymorphism would now be recognized as a useful character.

William Morton Wheeler (1935) made another major advance in rearranging the structure of the Melophorini, an arrangment largely retained in modern thinking on the group. Lasiophanes, Melophorus and Prolasius (the last including, however, two Notoncus species) assumed full generic status. The remaining genera in the tribe Melophorini were Diodontolepis (including Notoncus spinisquamis only), most of the remaining Notoncus under the genus of that name, Pseudonotoncus and Myrmecorhynchus. Wheeler removed a number of names from the existing genus Melophorus and reassigned them to Prolasius. Wheeler also tackled variation within Melophorus by erecting three subgenera: Melophorus sensu stricto for the gracile forms like M. aeneovirens (Lowne) that resemble the American honey-pot ants in the genus Myrmecocystus, Erimelophorus for the large-headed forms and Trichomelophorus for the peculiar M. hirsutus Forel.

The last major contribution to the taxonomy of Melophorus in its own right was made by Brown (1955). He dismissed Wheeler’s three subgenera on the basis of structure and habits and formally synonymized them. He also drew attention to two important diagnostic characters for the genus, namely, the long ‘ammochaetae’ (psammophore) together with the J-shaped setae on the mentum and also the elongate propodeal spiracle.

Since 1955 there has been no serious taxonomic consideration of the genus. Andersen (2000), in a field guide, provided a key to northern Melophorus that included very many groups. These groups appear to have been chosen on phenetic grounds, and the characters used, e.g., sculpture, pilosity, etc. were mainly those that have little validity at the species-group or subgenus level. A few characters used, such as length of the palps, have more significance, and they are discussed later in this work. A later discussion (Andersen 2007), evidently developed from the first (i.e., Andersen 2000), and covering a broader suite of Melophorus, is much more substantial, and (to our minds) accurately identifies some apomorphies that set apart several, although not all, significant species-groups that we recognize. In this case, Andersen subsumed such groupings under broader ‘radiations’. His identification of the M. fulvihirtus, the M. potteri and the M. aeneovirens species-groups are supported in this work, as, in general terms, are the characters used to differentiate them, viz., appearance of the palps, the presence or absence of metatibial apical spurs, and the clypeal apron (in the aeneovirens species-group). Nonetheless, not all the characters mentioned are correctly applied (e.g., the metatibial spur is not absent in M. fulvihirtus, as stated by Andersen). Other important characters, such as the placement of the clypeal psammophore, the shape and dentition of the mandible and the nature of the preapical metatibial spines, are discussed in this work.

Apart from Andersen’s two works, there has been little else on the genus since 1955. Two rather aberrant and interesting Melophorus, M. anderseni and M. majeri, were described by Agosti in 1997, the first new species to be described since Melophorus bruneus McAreavey in 1949. No Melophorus species have been described since 1997.

At a higher taxonomic level, Agosti (1991) used the unfused helcium (the collar-like pre-tergite and pre-sternite of the third gastral segment) and the close alignment of the hind coxae to place Melophorus in the Formica species-group. However, Bolton (2003) reverted to the traditional morphological argument based on the anatomy of the proventriculus, along with details of the mandible and metatibial setae, to situate Melophorus as the sole genus in the Tribe Melophorini. Recent molecular work (Moreau et al. 2006 using five nuclear genes and one mitochondrial gene) strongly supported an Australoid formicine clade comprising Myrmecorhynchus, Melophorus, Prolasius and Notoncus, confirming the suspicions of the early Twentieth century myrmecologists such as Forel, Emery and Wheeler. Finally, Ward et al. (2016), in a molecular phylogenetic study, posited a tribe Melophorini that consists of eight purely Australian genera (Melophorus, Myrmecorhynchus, Notoncus, Notostigma, Prolasius, Pseudonotoncus, Stigmacros and Teratomyrmex) and one South American genus, Lasiophanes. Interestingly, this paper confirms much of Wheeler’s earlier (1935) analysis, especially when one considers that the uncommon and localised genus Teratomyrmex had not yet been discovered.

Biology and ecology. Although the genus Melophorus is generally poorly known, several species, most notably Melophorus bagoti Lubbock, have been the focus of concentrated research. Much of the current interest in M. bagoti concerns homing strategies in this ant (e.g., Wehner et al. 2006, Narendra 2007a, Narendra 2007b, Legge et al. 2010); while more occasional research has covered nest structure and activity (Conway 1992), thermophilism (Christian and Morton 1992) and general biology and taxonomy (Wheeler 1908). Other Melophorus species that have received individual attention have been Melophorus perthensis (as ‘Melophorus turneri perthensis’) (Majer et al. 2011), an unidentified species in the Melophorus aeneovirens group (Hoffman 1998) and those taxa that feature in taxonomic papers with some commentary on the habits of the species described (e.g., Melophorus fulvihirtus, in Clark 1941, and Melophorus anderseni and M. majeri, in Agosti 1997).

In terms of general role in the environment, Melophorus ants are a highly thermophilic group that fills the same ecological niche as Cataglyphis in the Old world and Myrmecocystus in North America (Andersen 2007). All species are active only during the day, mostly at peak diurnal temperatures and predominantly in the summer months. Briese and Macauley (1980) found that one species (‘Melophorus sp. A’) studied at Emmet Vale, NSW, was only active when the temperature was between 37°C and 54°C, and this species was inactive for prolonged periods in the cooler months. Species are richest in arid or semi-arid environments, and relatively few inhabit thick forest or cooler, mesic areas. There are no alpine specialists. Typically, Melophorus species nest directly in soil (see Figure 1) and can rarely be found under stones or woody debris. Although they may forage on tree-trunks and vegetation no arboreal nesters are known. Soil nests of very common species such as Melophorus turneri and M. perthensis Wheeler are easily recognizable by the small, crescentic dunes of excavated sand that surround the nest hole (senior author pers. obs.). Melophorus nests are often or always closed with sand or pebbles at night (McAreavey 1947, current authors pers. obs.). Members of this genus are exceptionally timid ants, avoiding conflict with other ants (e.g., meat ants) by occupying a different temporal niche. They will also retreat into their nest upon the slightest human disturbance, and will not reemerge for several minutes (Shattuck 1999).

Figure 1. 

Melophorus nest entrances. a M. bagoti b M. gracilipes c M. longipes dM.marmar e M. mjobergi f M. perthensis g M. sulla, and h M. wheeleri.

Melophorus ants have a diverse range of diets, depending on the species, and some are quite specialized. Melophorus potteri McAreavey is a termite raider (McAreavey 1947, Andersen 2000), and its bluntly serrate mandibles with a single large apical tooth may represent an adaptation to this lifeway. Interestingly, raids are carried out by individual workers, and not columns of workers, as in many formicid termitophages. A second species in the M. potteri group (Melophorus pelecygnathus Heterick et al. this work) has extraordinary hatchet-shaped, edentate mandibles and may have similar behavior. However, the third species in this group (Melophorus macroschismus Heterick et al. this work) has the normal 5-toothed dentition of most Melophorus. Melophorus anderseni Agosti and Melophorus fulvihirtus Clark raid meat ants’ (Iridomyrmex purpureus species-group) nests. Clark (1941) mentions the raiding activity of M. fulvihirtus in a brief note, but Agosti’s (1997) observations on M. anderseni are outlined in detail: this latter species uses subtle behavioural characters and the scent of its host so that it can carry off meat ant pupae. Workers of this ant were seen by Agosti to actually rub themselves against meat ant workers in order to obtain their nest odour.

The M. wheeleri species-group, in which the major workers have powerful, truncate, inwardly curved mandibles, are said to be obligate granivores (Andersen 2007). In some cases, exotic plants with suitable seeds may have replaced the use of native species in the diet of members of this species-group: for instance, in southern WA, Melophorus wheeleri Forel is known to feed on the seeds of the exotic grass Avena barbata (Harris and Standish 2008).

Apart from such specialized forms, most Melophorus are omnivores but include a large amount of vegetable material in their diet. Berg (1975) concluded that Melophorus species have a strong preference for elaiosomes, the nutrient rich appendages found on the seeds of many Australian plants. Elaiosome-eating species such as M. perthensis are likely to play an important role in native seed germination (Majer et al. 2011). Melophorus perthensis is one of the major seed harvesters in the West Australian jarrah forest (Majer 1982). Davidson and Morton (1981), who examined seed removal in inland NSW, found that diaspores (seeds modified for dispersal) moved by ‘Melophorus sp. H’ tended to be in the smaller range (» 4.09 mg). Animal protein in the case of omnivores may be supplied in the form of insects roasted in desert heat (Narendra 2007a) or dead ants discarded by their nestmates (Briese and Macauley 1981). Such scavenged Formicidae can constitute a surprisingly high percentage of food items: Briese and Macauley’s study includes tabular information that 40% of the food items taken back to their nest by an unnamed Melophorus species (‘Melophorus sp. A’) were of this nature. Several gracile species forage on the trunks of eucalypts. Greenslade (1979) states that one such species, with a peculiarly flattened head, is adapted to foraging under bark. Melophorus may attend lycaenid butterfly larvae that produce sugary glandular secretions, but known associations of lycaenid larvae with this genus of ants appear to be relatively minor and purely facultative (Eastwood and Fraser 1999, Fiedler 2001).

In turn, Melophorus species, especially their alates, are an important food source for some agamid lizards (e.g., they are one of the few sources of food for the Lake Eyre dragon lizard Ctenophorus maculosus Mitchell [Chan et al. 2009]), other ants (e.g., Iridomyrmex) and spiders (a zodariid spider is mentioned as an important predator of Melophorus bagoti by Muser et al. 2005). On the other hand, non-agamid lizards prefer termites over ants (Abensperg-Traun and Steven 1997). Information on Melophorus as a dietary item for other Australian vertebrates is sketchy at best and usually lacking. Melophorus species are rare in the diet of numbats (Calaby 1960), and there is little or no specific information on genera of ants, other than Iridomyrmex, included in the food intake of other ant-eating mammals such as echidnas and several smaller carnivorous marsupials that will eat ants. Insectivorous snakes may take Melophorus, although there is just the one record of Melophorus as a prey item (for Ramatyphlops australis) in the list of ant genera eaten by blind snakes (Typhlopidae) supplied by Webb and Shine (1993). Melophorus alates, presumably, also run the risk of predation by birds. Worker ants, however, are probably not taken by most birds because of the uncomfortably high temperatures at which they are active and their speed over the ground surface. Replete workers of Melophorus bagoti are famous as food for desert dwelling Aboriginal people, but some references to their use are qualified (e.g., Conway 1992) or reject that repletes of M. bagoti are acceptable as human fare (thus, Australian Myrmecology Gallery 2002).

Homing strategies. Melophorus bagoti (and, in all likelihood, other desert-dwelling species of Melophorus) uses a type of homing device called path-integration that enables ants to return to their nest along the shortest return route in a featureless environment (Narendra 2007a). Presumably, this type of orienting also compensates for the difficulty in following pheromone trials laid on shifting or unstable, windblown soils. Ants may also be blown off their paths by dust storms (Narendra 2007b). In a carefully manipulated experiment, Legge et al. (2010) pursued this question further. Where path integration information was not available, M. bagoti workers did not use visual landmarks (artificially provided in the study). Instead, they oriented in a particular direction (in this case the exit from an artificial arena) regardless of whether or not it was aligned with the ants’ nest. Thus, it appears that vectors used by the ant to return to its nest are based on compass information gleaned from previous trips, i.e., the path integrator does not process information based on the current journey. The nature of the landmarks that enable these ants to learn local vectors in natural circumstances have not been determined as yet, but Legge et al. surmise that possibly the skyline is a factor, as is polarized light.

The current position of Melophorus. This genus is currently very poorly characterized considering its importance in the Australian landscape. At the time of writing there are only 24 full species and eight subspecies in the taxonomic literature. One taxon (Melophorus cowlei Froggatt, here reinstated as a junior synonym of Melophorus bagoti) was misidentified for quite a large portion of its history as a Camponotus. The lack of taxonomic activity, especially in regards to the smaller species, is quite puzzling. Synonymy is extensive, and clusters around a small handful of the larger and more ubiquitous taxa (namely, M. aeneovirens, M. biroi Forel, M.turneri and M. wheeleri). Much of the descriptive work took place in the era 1900-1930 (see Figure 2), which corresponds to the most productive period of the great continental taxonomist-systematist Auguste Forel, who described almost fifty per cent of the Melophorus fauna prior to this monograph. After 1930 the description of new Melophorus species has largely been the province of the amateur researcher Father John J. McAreavey and the economic entomologist John Clark.

Figure 2. 

Numbers by decade of new species of Melophorus appearing in the taxonomic literature since 1865 (when Melophorus aeneovirens was described).

Biomonitoring Potential. In Australia, Melophorus ants are currently an important component in the Ant Functional Group (e.g., Andersen 1990, 1995) mix used by researchers and land managers to investigate the success of minesite, rangeland and burnt area rehabilitation. However, their thermophilism also makes them a potential candidate in investigations into microhabitat alteration as climate and weather patterns change under the influence of global warming. Hypothetically, the natural range of many species may be expected to be extended with increasing aridity and higher average temperatures, particularly in the south west of the Australian continent.

Melophorus is deserving of closer scientific scrutiny for a variety of reasons. Not only is it one of the largest Australian ant genera, being more speciose and biologically diverse than genera like Iridomyrmex and Monomorium, but its importance in the fabric of many Australian ecosystems and its biomonitoring potential may be even greater than the abovementioned groups. Unrelated areas of research involving Melophorus ants, such as the analysis of thermophilic activity, orientation using path-integration and the dispersal of elaiosome-producing seeds, have already become well-established, and members of this genus undoubtedly have other adaptations that could be identified and studied with profit.

As a final note, in the field most members of this genus of ants are extremely difficult to catch because of their rapid movement across the ground. The senior author found that major workers and minor workers of large species could be slowed without damage by dabbing gently at them with cotton wool impregnated with ethanol, and then picking the ants off the cotton wool with forceps. Minor workers were collected by suctioning – mainly at the entrance to their nest – with a pooter and transferring them immediately to an ice bath (i.e., a basin filled with ice and water). This had the effect of paralyzing these thermophilic organisms so that they lay quiescent on the water surface and could be transferred with ease to a vial of ethanol.

Phylogeny: materials and methods

The procedure followed here is that results of the molecular work will be presented first, culminating in a reconstructed evolutionary tree, and then will follow the morphological taxonomic results and discussion.

Sources of material and images

The following Museums and research institutions provided loans or images or otherwise assisted with making material available for this study:

AMS Australian Museum, Sydney, Australia.

ANIC Australian National Insect Collection, Canberra, ACT, Australia.

BMNH The Natural History Museum, London, UK.

CASC California Academy of Sciences, San Francisco, California, USA.

HNHM Hungarian Natural History Museum, Budapest, Hungary.

JDM Curtin Ant Collection, Curtin University of Technology, Perth, Western Australia, Australia (now amalgamated under WAM–see below).

MCZ Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA.

MHNG Muséum d’Histoire Naturelle, Geneva, Switzerland.

MSNG Museo Civico di Storia Naturale ’Giacomo Doria’, Genoa, Italy.

NHMB Naturhistorisches Museum, Basle, Switzerland.

QM Queensland Museum, Brisbane, Queensland, Australia

SAMA South Australian Museum, Adelaide, South Australia, Australia.

SMNH Naturhistoriska riksmuseet, Stockholm, Sweden

WAM Western Australian Museum, Perth, Western Australia, Australia.

ZHMB Museum für Naturkunde der Humboldt Universität, Berlin, Germany.

Abbreviations of depositories

Novel type material (holotypes and paratypes) was deposited in the following institutions: ANIC, BMNH, MCZ, QM and SAMA. Note: Although it did not provide material or images, reference is also made in this monograph to The Tropical Ecosystems Research Centre (TERC), centred in Darwin, Northern Territory, Australia.

Measurements and indices (Figure 3)

Major and minor workers of each species have been included in the measurements where possible. However, for some uncommon species only minor or major workers are known. Size and shape characters were quantified and are reported as lengths or indices. Measurements were made with a stereomicroscope using a dual-axis stage micrometer wired to digital readouts. All measurements were recorded in thousandths of a millimetre, but expressed here to the nearest hundredth. The following measurements and indices are reported (readings are presented in mm).

EL Eye length: maximum length of the eye measured in profile

HL Head length: maximum head length in full-face (dorsal) view, measured from the anterior-most point of the clypeal margin to the midpoint of a line drawn across the posterior margin of the head.

HW Head width: maximum head width measured in full-face (dorsal) view, excluding the eyes.

ML Mesosomal length: mesosomal length measured from the anterior surface of the pronotum proper (excluding the collar) to the posterior extension of the propodeal lobes.

MTL Maximum tibial length: maximum length of the tibia of the middle leg, excluding the proximal part of the articulation which is received into the distal end of the femur.

PpH Propodeal height: maximum height of propodeum measured tangentially from a line drawn between the metanotal groove to the posterior extension of the propodeal lobes.

PpL Propodeal length: length of propodeum measured from the metanotal groove to the posterior extension of the propodeal lobes.

SL Scape length: scape (first antennal segment) length excluding the basal neck and condyle.

CI Cephalic index: head width (HW)/head length (HL) × 100.

EI Eye index: eye length (EL)/head width (HW) × 100.

SI Scape index: scape index: SL/HW × 100.

Figure 3. 

Frons of head of Melophorus showing structures mentioned in this monograph: AS antennal scape AT apical tooth BT basal tooth CI compound eye CS clypeal psammophore, consisting of a fringe of setae (nb. only those on RHS of head labelled) FC frontal carina FT frontal triangle M mandible OT ocellar triangle, consisting of three ocelli (simple eyes) T torulus TP tentorial pit; 2, 3, 4, tooth sequence commencing from the apical tooth.

Molecular phylogenetics

Tissue collection. Specimens were collected by hand and placed into 100% ethanol.

DNA extraction. A non-destructive DNA extraction method, ANDE (Castalanelli et al. 2010) was used to extract DNA from all the specimens used in this study.

Amplification and Sanger sequencing. For specimens M001-M154 and M303-M356, amplification of the five genes (COI, LR, Wg, AA, and H3) was performed using the primers outlined in Table 1. PCR amplification volumes were 25 µl, including 2.5 µl of ANDE extracted DNA (1:10 dilution DNA:water) which was the equivalent of 20 to 25 ng/µl. The reaction mix comprised of 1 × polymerase buffer (Bioline; MyTaq), 0.2 µM of each primer. The thermocycler conditions were: 95 °C for 10 min; 40 cycles of: 95 °C for 30 s, annealing for 30 s, and 72 °C for extension, with a single final extension.

Quality and quantity of the amplified PCR products were determined on a 1.5% agarose gel. Sequencing of the amplified genes was carried out by AGRF (Australian Genomic Research Facility) using an Applied Biosystems ABI 3730 48-capillary DNA analyser with Big Dye Terminator Technology according to the manufacturer’s protocols (Applied Biosystems).

Table 1.

Primers used during this study.

Gene Primer Name
mT COI (COI) LCO1490 5'-GGT CAA CAA ATC ATA AAG ATA TTG G-3' Folmer et al. 1994
HCO2198 5'-TAA ACT TCA GGG TGA CCA AAA AAT CA-3' Folmer et al. 1994
Jerry 5'-CAA CAT TTA TTT TGA TTT TTT GG-3' Simon et al. 1994
CI-J-1718 5'-GGA GGA TTT GGA AAT TGA TTA GTT CC-3' Simon et al. 1994
nDNA Wingless (Wg) Wg578F 5'-TGC CAN GTG AAR ACY TGC TGG ATG CG-3' Ward and Downie 2005
Wg1032R 5'-ACY TCG CAG CAC CAR TGG AA -3' Abouheif and Wray 2002
nDNA Abdominal-A (AA) ant-M 5'-CGG CAC CGG CGA TAT GAG TAC GAA ATT C-3' De Menten et al. 2003
ant-J 5'-GGG TTG TTG GCA GGA TGT CAA AGG ATG-3' De Menten et al. 2003
nDNA Rhodopsin (LR) LR143F 5'-GAC AAA GTK CCA CCR GAR ATG CT-3' Ward and Downie 2005
LR639ER 5'-YTT ACC GRT TCC ATC CRA ACA-3' Ward and Downie 2005
nDNA Histone 3 (H3) H3F 5'-ATG GCT CGT ACCAAG CAG AC(ACG) GC-3' Colgan et al. 1998
H3R 5'-ATA TCC TT(AG) GGC AT(AG) AT(AG) GTG AC-3' Colgan et al. 1998

Amplification and amplicon sequencing. For specimens M155-302, amplification of the five genes gene was performed using the primer outlined in Table 1, with the additional M13 sequences 5'-GTAAAACGACGGCCAGT-'3 and 5'-AACAGCTATGACCATG-'3, added to the 5' end of the forward and reverse sequences, respectively. PCR volume was 25 µl, including 2.5 µl of ANDE extracted DNA (1:10 dilution DNA:water) which was the equivalent of 20 to 25 ng/µl. The reaction mix comprised of 1 × polymerase buffer (Bioline; MyTaq) and 0.2 µM of each primer. The thermocycler conditions were: 95 °C for 10 min, 40 cycles of: 95 °C for 30 seconds, annealing for 30 seconds, and 72 °C for extension; with a single final extension of 72 °C for 30 s for 5 minutes.

To prepare the amplicons for next generation sequencing a second round of PCR amplification was performed. The primers consisted of the Roche Lib-A adapters (Roche), a unique multiplex identifier (MID) sequence, and the complementary M13 sequence. In total 96 unique primer sets were constructed so that batches of 96 samples could be pooled and analysed at once. PCR volume was 25 µl, including 2.5 µl of first round amplifcation extracted DNA (1:100 dilution DNA:water). The reaction mix comprised 1 × polymerase buffer (Bioline; MyTaq) and 0.2 µM of each primer. The thermocycler conditions were: 95 °C for 10 min; 10 cycles of: 95 °C for 30 seconds, annealing for 30 seconds, and 72 °C for extension; with a single final extension.

Quality and quantity of the amplified PCR products were determined on a Labchip GXII (Perkin Elmer) using the HT 1K LabChip (Perkin Elmer). For each gene, the successfully amplified PCR products were normalised to 1ng/uL and pooled. Each gene pool was purified using the E-Gel® SizeSelect™ Gels (Thermofisher), then further purified using Agencourt AMPure XP (Beckman Coulter) as per the manufacturers’ instructions. The quantity of each gene was determined on a Labchip GXII (Perkin Elmer) using the HT 1K LabChip (Perkin Elmer) and each gene mixed to an equimolar concentration, term library. The library was diluted 1 in 1,000 and further purified twice using Agencourt AMPure XP as per the manufacturers’ instructions. The library was quantified using quantitative PCR as per Bunce et al. (2012) and diluted to approximately 2 million copies. The GS Junior sequencing run was set up as per the manufacturers’ instructions, and run for 200 flows.

Data analysis. The data were exported in fasta format and analysed using a self-written bioinformatics script based in Python (Python Software Foundation). Each sequence was analysed for its MID and primer sequence, which allowed the sequence to be assigned back to its specimen identification number and gene with all associated sequences saved in a single fasta file. For each specimen, the fasta file for each gene was imported in Geneious research software (BioMatters) and assembled and checked for sequencing errors. Low-occurring single nucleotide polymorphisms (SNP) were ignored, but where an SNP was >30% an IUPAC (International Union of Pure and Applied Chemistry) code was used. Each gene was translated using the standard invertebrate mitochondrial and nuclear codes, where applicable, to detect the presence of nuclear mitochondrial DNA (NUMTs).

Phylogenetic analysis. Phylogenetic relationships among each of the complexes and species were assessed using *BEAST (Drummond et al. 2012). To test the complexes proposed here, individuals were grouped according to their complex and similar species were grouped together according to their morphological identification. Each of the five genes was systematically tested using the substitution models General Time Reversible (GTR), Hasegawa-Kishino-Yano (HKY), Jukes-Cantor (JC) and clock models (strict and lognormal). Due to the high divergences within the COI gene, this data set was split and the first and second codon bases were examined with and without the third base. Each of these combinations were evaluated with gen=10,000,000, log=1000. Evolutionarily Stable Strategy (ESS) scores were evaluated for each run to determine which model was the best for each gene. The final tree models were HKY for the genes AA, Wg, and H3, and GTR for COI and LR. Strict clock rates were run for all genes for 50,000,000 generations and logged every 5,000 generations.

Evolutionary history

BEAST (Drummond and Rambaut, 2007) was used to estimate temporal distance between target taxa and their most recent common ancestor (Time to Most Recent Common Ancestor, or TMRCA). This program is suitable for evaluating rooted, time-based phylogenies using strict or relaxed molecular clocks; it is also useful as a framework for testing evolutionary hypotheses by focusing on multiple tree topologies, rather than merely a single tree. BEAST uses the Markov Chain Monte Carlo (MCMC) algorithm sampling method to average across tree space (i.e., the dimension that includes all possible trees), so that each tree is weighted proportionally to its posterior probability. In our case, only four out of the five genes were selected due to the availability of other Formicinae sequences deposited on genbank (NCBI). The evolutionary clock model Generalised Time Reversible (GTR) was applied to the LR and COI genes. In contrast, the Hasegawa, Kishino and Kano (HKY) model was applied to the AA and Wg genes. These models were selected as they each provided optimal ESS scores. No Melophorus fossils are known (http://antwiki.org/wiki/Checklist_of_Melophorus_species), so were not available for this exercise. The first node, including the root height parameters, was offset to 145 million years ago (Ma ago) with an exponential prior distribution and a mean of 10 Ma, which returned quantiles of 145.5 and 175.0 Ma ago, i.e., 5% and 95% respectively. The lower boundary represented the date calculated by Brady et al. (2006), while the upper boundary corresponded to the MRCA boundary for ants calculated by Moreau et al. (2006). The second node calibrated the MRCA for the Melophorini group, which was set with an exponential prior distribution offset to 52.6 Ma ago (the lowest date calculated by Blaimer et al. (2015) and mean 7 Ma, which returned an upper quantile of 78.42 Ma ago. This upper bound coincides with the vicariance event of Australia splitting from New Zealand and New Caledonia (80–60 Ma ago) (Stevens 1989, Yan and Kroenke 1993). These bounds are also supported by the placement of the South America genus Lasiophanes within Melophorini (Ward et al. 2016).

Results

Mitochondrial and nuclear sequence data

Forty-six taxa from the M. aeneovirens, M. biroi, M. ludius and M. potteri species-groups produced useable sequences (Table 2). No representatives of the M. anderseni or M. majeri species-groups were available for analysis, and a single representative of the M. fulvihirtus species-group failed to produce a useable sequence The number of samples amplified for each gene ranged from 116 (AA) to 141 (Wg). In total, 83 individuals from 33 species were successfully sequenced for all five genes, and these constitute most of the species discussed in the section dealing with molecular analysis.

Within the genus Melophorus the COI gene fragment was the most divergent with a maximum interspecific divergence of 17.3% (Table 3.). Similarly, the intraspecific divergence was four time higher than that for the nuclear genes. Several species had COI intraspecific divergences >5%; these included M. bagoti, M. biroi, M. perthensis, M. rufoniger, M. sulla, M. turneri, and M. wheeleri. As expected, the nuclear genes were considerably more conserved than the mitochondrial gene and ranged from an average intraspecific distance of 0.87% to 1.89% for AA and H3, respectively. The minimal divergences within the nuclear genes are reflected in the lack of clarity they bring when included in the species trees.

Table 2.

Taxonomic groups and the number of gene sequences generated.

Group Complex Species AA COI H3 LR Wg
aeneovirens aeneovirens canus 1 1 1 1
griseus 1 1 1 1
platyceps 1 1 1
praesens 1 1 1 1 1
rufoniger 3 3 1 3 3
sulconotus 1 1 1 1
teretinotus 1
bagoti bagoti 7 7 8 9 9
gracilipes 3 4 4 4
nemophilus nemophilus 1 1 1 1 1
biroi biroi biroi 6 8 7 8 8
graciliceps 2 3 3 2
gracilis 2 3 4 3 4
lissotriches 1 1 1 1
mjobergi 7 7 7 7 7
postlei 1 2 2 2 2
brevignathus marmar 2 2 2 2 2
fieldi ankylochaetes 2 2 2 2 2
bruneus 1 1 1 1
eumorphus 1 1 1 1 1
fieldi 1 1 1 1
fulvidus 1 1 1 1 1
hirsutipes 3 5 5 5 5
incisus 2 2 2 2 2
inconspicuus 1 1 1 1 1
lanuginosus 6 4 6 6 6
longipes 4 5 5 5 5
microtriches 5 4 5 5 5
perthensis 5 6 5 6 6
sulla 6 5 5 6 6
turneri 15 14 18 18 18
vitreus 1 1 1 1 1
wheeleri chauliodon 1 4 4 4 4
caeruleoviolaceus 1 1 1 1 1
laticeps 1 1 1 1 1
parvimolaris 1 1 1 1 1
pelorocephalus 2 2 2 2 1
purpureus 1 1 1 1 1
wheeleri 11 10 12 11 14
xouthos 1 1 1 1 1
oblongiceps oblongiceps 1 1 1 1
ludius hirsutus hirsutus 1 1 1 1
ludius ludius 1 1 1
pusillus 1 1 1 1 1
translucens 1 2 2 2 1
potteri potteri potteri 2 1 2 2 2
Total 116 126 123 137 141
Table 3.

Maximum pairwise sequence divergence within species, for the five genes in this study. Blank cells indicate that only one specimen was sequenced for that gene-species combination.

Species AA COI H3 LR Wg
ankylochaetes 0 0.9 0 0.2 1
bagoti 0.9 8.3 11 2.5 1.1
biroi 1.7 10.8 9.2 1.4 2.5
chauliodon 2.5 1 2.7 1.3
gracilis 1.1 0.9 0 1.4 1.5
hirsutipes 0.3 7 1.9 0.5 2.2
incisus 0.9 0 0.7 0 0
lanuginosus 1.3 4.7 1.3 2.2 0.8
marmar 0 0 0.3 0.9 0.8
microtriches 0.3 1.2 0.5 0.4 0.5
mjobergi 0.8 1.4 3 0.8 2.4
pelorocephalus 0 0 0.7 0
perthensis 0.3 5.5 0.7 1.3 1.6
postlei 1.2 0.7 0.3 0.4
potteri 0 0 0 0
rufoniger 1.3 10 1.1 2.4
sulla 1 8.9 0.7 2.3 1.4
translucens 0 0 0.2
turneri 3.3 11.8 2.3 2.5 2.8
wheeleri 0.8 7.8 2.3 2.2 2.8
Average Intraspecific 0.87 4.15 1.9 1.2 1.4
Maximum Interspecific 4.1 17.3 12 7.1 6.5

Phylogenetic analysis and discussion

Overall, the results of the species-level tree (Figure 4) are concordant with the morphology. The species tree reveals well supported clades at the complex level with the most prominent exception being M. chauliodon (which aligns with the M. fieldi complex based on the genetics, although the mandibular morphology of the major worker would seem to place it within the M. wheeleri complex). However, a three-gene species tree (Suppl. material 1) constructed using the LR, Wg and COI genes strongly places M. chauliodon within the M. wheeleri complex. In fact, our conclusions based on the morphological appearance of the taxa is that the three-gene tree appears to corroborate some of the relationships suggested by the morphology more than does the five-gene tree. This may be due to confusion arising from uninformative signals from the histone and Abdominal-A genes in the latter. Thus, in the three-gene tree, M. fulvidus and M. chauliodon (as mentioned above) are placed near to taxa with which they share anatomically significant structures. In the five-gene tree they appear out of place. Indeed, most species anatomically associated with the M. wheeleri complex and the M. fieldi complex also show corresponding associations within the three-gene tree. The placement of M. xouthos and M. parvimolaris in the M. wheeleri complex, however, is supported by the five-gene tree but not the three-gene tree.

Figure 4. 

Phylogenetic species tree for five genes. Species-groups and complexes are colour-coded. Outgroups include Notoncus gilberti, Nylanderia glabrior, Leptanilla sp., Strumigenys pulchella, and Aenictus sp. Each vertical color-bar links taxa of the same species-group or species-complex. Numbers above lines represent branch support; the scale bar refers to genetic change of 0.002 nucleotide substitutions (‘sc’ = species-complex; ‘sg’ = species-group).

A significant exception to the general concordance of morphology and genetics is the position of the taxa Melophorus hirsutus, M. pusillus and M. translucens on both three-gene and five-gene species trees. The clade including these three ants exhibits an unexpectedly basal relationship to indisputable members of the M. biroi species-group. This is counterintuitive, as their morphology would support a close relationship between these taxa and those within the M. mjobergi-biroi clade, let alone the broader species-group. However tempting it might be to suggest that sequencing issues were responsible for this unexpected result, the algorithm used produced the same disconcerting result for individual gene trees as well as multiple gene trees, so that it cannot readily be thought of as artificial (but see further discussion under Evolutionary history discussion).

The sister-species relationships are in contrast to the generally strongly supported broader evolutionary patterns; for example, the relationships within the M. fieldi and M. wheeleri complexes are only weakly supported. The lack of support reflects the choice of genes: the mitochondrial gene was strongly divergent with high levels of homoplasy at the third codon base. When analysis was conducted with the third base incorporated, several species became polyphyletic and the ESS scores dropped below 200. However, the removal of the third base dramatically increased the ESS scores and rendered almost all species monophyletic, apart from M. biroi, M. turneri, M. sulla, and M. hirsutipes.

Given that the removal of the third codon base still left consistent paraphyly or even polyphyly for M. turneri, M. sulla and M. hirsutipes, other explanations for this phenomenon are required. The most obvious one is incorrect identification. (We confess here that the inaccurate identification of these sometimes maddeningly similar little ants accounted for many early sequencing discrepancies before good diagnostic characters could be discovered!) However, even after careful checking and rechecking, the three taxa mentioned continued to pose problems requiring a different explanation. Firstly, the splitting could be indicative of sibling or cryptic species not identified by morphological analysis. The high pairwise divergence among the three species (> 5%) might suggest this explanation. This is less likely to be the case with M. hirsutipes in which the degree of genetic divergence is less pronounced (7.8% compared with 11.8% in M. turneri and 8.9% in M. sulla), although there is a greater degree of physical variability among M. hirsutipes workers than there is in the other two taxa. In the case of M. hirsutipes also, the three-gene tree showed results (e.g., the placement on the tree of samples M153 and M323) that were disparate compared with the results of other trees. In the three-gene tree (strongly influenced by the COI configuration), M153 and M323 are on different branches, but they are sisters in the Wg tree. Similar results occurred with M. turneri. This suggests possible hybridisation. The senior author found likely hybrids of M. turneri and M. bruneus north of Wiluna, and incomplete speciation or, at least, relatively high gene flow between more-or-less discrete species, may also account for the polyphyly seen. Thirdly, since genotype does not automatically match phenotype, the trees could be illustrating incomplete lineage assortment, with more than one allele found in the genes used for a given species represented in the sequencing. Since these three species are all very common ants that occur across a wide range of ecosystems throughout Australia, incomplete lineage assortment is a possibility that should also be investigated.

Possibly one or a combination of these three interpretations (and there are other possibilities) could account for the differences seen on the trees for these three similar but morphologically discrete species. Perhaps the greatest likelihood, given their strongly derived position in the three-gene tree, is that the incidence of multiple alleles through frequent mutations in the mitochondrial gene COI due to rapid evolution is very high in these taxa. The field evidence of possible hybridization in this Melophorus complex may also indicate the fixation of the speciation process is not yet complete for M. hirsutipes, M. sulla and M. turneri (this could also be the explanation for separation of samples for the same taxon in the slower evolving Wg tree).

The issues surrounding M. biroi (which occupies a much more basal position on the five-gene tree) are more substantial, and this taxon is likely a complex of two or more species (displayed in Figure 5). This matter is discussed further under the individual species accounts.

Figure 5. 

Calculated dates of divergence for TMRCA for Melophorus and other sample formicine taxa, including several of the postulated nearest relatives of Melophorus (i.e., other Melophorini). Outgroups are Apis mellifera and Protanilla sp.

Evolutionary history discussion

The phylogenetic history of Formicidae and, to a lesser extent, Formicinae, has been discussed extensively by Moreau et al. (2006) and Brady et al. (2006). These two groups of authors suggest that TMRCA of formicoids/poneroids and leptanillines lived between 116 (Brady et al. 2006) and 156 (Moreau et al. 2006) Ma ago, with the advent of the Formicinae ranging from 77 (Brady et al. [2006]) to 92 (Moreau et al. [2006]) Ma ago. More recently, Blaimer et al. (2015) has provided further insight into the Formicinae and its constituent tribes. Our chief aim in this work was to estimate the divergence dates for the species-groups within Melophorus (Table 4).

Table 4.

Summary of divergence dates (Ma ago) here proposed for select crown taxa including Melophorus species-groups and complexes.

Subfamily Ma ago
Leptanillinae 149,56
Formicinae 103,65
Tribe
Melophorini 57,03
Genus
Melophorus 35,43
Species-Group
aeneovirens 21,14
Species complex
bagoti 11,03
biroi 21,88
ludius 27,77
fieldi 13,32
wheeleri 16,42

Based on the estimated ages of this study, we propose that the Formicinae arose significantly earlier than the 77 Ma ago estimated by Brady et al. (2006), and closer to the dates estimated by Moreau et al. (2006) and Blaimer et al. (2015). Furthermore, formicine fossil records suggest a MRCA exceeding 92 Ma ago (Grimaldi and Agosti 2000), which is within the parameters of our data. The MRCA of 57.03 Ma ago for Melophorini (congruent with Blaimer et al. [2015]) coincides with the vicariance events that led to the separation of Australia from New Zealand and New Caledonia (80-60 Ma ago [Stevens 1989, Yan and Kroenke 1993]). The inclusion of the genus Lasiophanes by Ward et al. (2016), which is endemic to South America, also supports this date. For organisms other than ants, the link between South America and Australia flora and fauna and New Zealand has been well documented for this period (e.g., mostly extinct lineages of southern beech (Nothofagus) (Cook and Crisp 2005), marsupials (Mitchell et. al 2014, Nilsson et al. 2004, Nilsson et al. 2010), and Diptera (Yeates and Wiegmann 2005). The other Melophorini are almost entirely restricted to Australia. The sole exceptions are Prolasius advena, which is endemic to New Zealand but has Australian affinities (http://www.landcareresearch.co.nz/publications/factsheets/Factsheets/prolasius-advenus), and Notoncus gilberti, which is widespread on the mesic east and south-west coasts of Australia. This species has also been recorded from New Guinea (http://www.antwiki.org/wiki/Notoncus_gilberti) but could conceivably have been introduced by human agency. Within the Melophorini the origins of Melophorus were estimated to be ~35Ma ago, again congruent with Blaimer et al. (2015).

Within the Melophorus genus, M. hirsutus shares a MRCA with the remainder of the species sampled that is estimated at ~35 Ma ago. Not only does this ant have several unique attributes (i.e., the virtual absence of a metanotal groove, a translucent lamina surrounding the pronotum, and distinctive conical or sub-conical eyes and protrusive antennal sclerite [this latter seen only in one population of another, unrelated Melophorus species]), it is phylogenetically basal and remains one of the few Melophorus to favour a mesic environment. Within Australia, this species is confined to the wet east coast and is not found much west of the Great Dividing Range. During the period in which Melophorus hirsutus appears to have arisen, Australia was experiencing moist climatic conditions but started to dry out during the middle of the Miocene (23-5 Ma ago). Temperatures became more elevated in the period 21-14 Ma ago. After 14 Ma ago, temperatures dropped sharply. Acidification of waterways in central Australia continued to increase and river systems reduced their output and became salt lakes (White 1994).

Based on our molecular findings, this coincides with the period in which rapid diversification within the M. fieldi complex occurred (Figure 6). The M. fieldi complex is the most speciose group within Melophorus. These findings corroborate other studies that support the hypothesis that the aridification of Australia has led to rapid diversification of plants, marsupials, and various reptile groups (see table 1 in Byrne et al. 2008).

Classification and taxonomy: results

Melophorus Lubbock, 1883

Melophorus Lubbock 1883: 51. Type-species: Melophorus bagoti, by monotypy.

Erimelophorus Wheeler 1935: 71. (described as a subgenus of Melophorus; junior synonym of Melophorus by Brown 1955: 474). Type-species: Melophorus wheeleri, by original designation.

Trichomelophorus Wheeler 1935: 71. (described as a subgenus of Melophorus; junior synonym of Melophorus by Brown 1955: 474). Type-species: Melophorus hirsutus, by original designation.

Worker diagnosis

Polymorphic ants characterized by a combination of long, J-shaped setae on the mentum, an elongate (often slit- or comma-shaped) propodeal spiracle, presence of a metapleural gland, antennal insertions abutting the posterior clypeal margin and three ocelli in an ocular triangle in all workers. The genus is taxonomically compact, and with the above characters taken into consideration, its members cannot be mistaken for any other group of ants. The descriptions below relate to the small minor worker and the large major worker. Media workers are of intermediate appearance but more closely resemble the minor worker.

Queen diagnosis

Larger to smaller than the conspecific major worker. Palp formula, ocelli, appearance of antenna and number of antennal segments, and number of mandibular teeth are as for the conspecific major worker. Mesoscutum about as wide as long in species seen. Parapsidal lines parallel and usually distinct. Axillae small and widely separated, the separation much greater than their width. The wing is of the ‘Camponotus’ form, with a radial cell, a first cubital cell and one submarginal cell. The cross-vein cu-a is present but the discoidal cell and cross vein m-cu are absent. Ergatoid or brachypterous queens have not been identified.

Male diagnosis

(Caution: this diagnosis is based on only a small number of specimens that we have been able to identify as Melophorus males). Males with typical characteristics of males of this subfamily. The head bears an ocellar triangle that may be weakly turreted in some species, the antennal scape is usually longer to much longer than the head and the 13-segmented antenna is elbowed. The eyes are generally larger than those in the corresponding queen or major worker but not globose or bulbous in males seen. The mandible is 1- to 4-toothed in males seen; if 1-toothed, then apical tooth is prominent. The wing is as for the queen, but in one species a second small submarginal cell may be present, possibly limited to certain individuals. The parapsidal line is always present, weakly to strongly impressed; the notaulus is absent or present only as a median appendix arising from the base of the mesoscutum. The axillae are small and very widely separated from one another, the separation much greater than their width. Workerlike, wingless males are known for at least one desert-dwelling species.

Worker description

Minor worker. Head. Head oval, square, cordate or rectangular, its posterior margin strongly convex to strongly concave. Compound eyes always present, usually medium to large (eye length generally 0.2× length of side of head capsule ≥), rarely small. Eye shape elliptical across most species, often slightly reniform due to an invagination of cuticle on the outer margin of the eye, much more rarely ovoid, roughly circular or oval tending to elongate; in some populations of M. hirsutus eyes flattened and embedded in cuticular prominences when seen in full-face view, or projecting roundly or even bizarrely conical. In full-face view, eyes mostly situated in the upper half of the head capsule, rarely (mostly in very small minor workers) at about the midpoint of the capsule, but never anteriad of the midpoint. In profile, eyes usually placed ahead of the midline of the head capsule, less frequently at about the midline or fractionally in front of it, but never behind the midline. Three small ocelli always present. In full-face view, frontal carinae convex, concave, straight, convergent posteriad or divergent posteriad, sometimes raised (particularly near antennal insertion), vestigial beyond antennal insertions in a few taxa. Torulus (antennal sclerite) pedunculated in a couple of species but otherwise inconspicuous. Antenna always 12-segmented. Scape very variable in length, but usually attaining the posterior margin of the head capsule, and often extending well beyond it. Clypeus never longitudinally carinate, or with protruding clypeal teeth but otherwise variable in appearance. Posterior margin of clypeus mostly arched and falling away from its mid-sector (i.e., between the frontal carinae), but lateral sectors of clypeus on same plane as mid-sector in a few species. Anterior clypeal margin often convex, with or without an anteromedial dimple, but concave, acuminate, spatulate and variously protrusive clypeal morphologies also occur. The midpoint of the clypeus may be notched, especially in the aeneovirens species-group. A clypeal psammophore of long setae (or ammochaetae) stretched across that sclerite is found in all Melophorus species, and may be located at any elevation, from at or just above the anterior clypeal margin to just under the posterior clypeal margin. Mandibular and gular psammophores of long, curved setae also usually present. Mouthparts. Palp formula mostly 6,4, but 3,4 and 3,3 also occur, maxillary palps variable in length from not reaching the hypostomal bridge to attaining the mesopleuron when they are fully extended. Apical segment of maxillary palp usually oblongiform, but may be narrow and acuminate or even vestigial and barely visible under a stereomicroscope. Mandible most commonly with five distinct teeth, but number of teeth and denticles ranges from four to over 15, mandible edentate except for apical tooth in one species. In five-toothed species apical tooth is nearly always much longer than remaining teeth and teeth 2 and 4 are typically longer than tooth 3 (teeth count taken from apical to basal tooth), basal tooth often offset and directed vertically. Masticatory margin usually vertical or weakly oblique, but strongly oblique in a few species. Mesosoma. Spines or denticles always absent from pronotum and mesonotum, present on propodeum only in M. majeri. Posterior pronotum planar, rounded or angled. Mesothoracic spiracles often opening on small dorsal prominences, these prominences stalk-like in M. hirsutus. Mesopleural process absent. Mesopleuron folds over onto flattened mesosternum without being demarcated by strong carina. Dorsal face of propodeum may be uniformly convex to flat, abruptly conical, or convex anteriad and flattened posteriad. Propodeal angle commonly absent, but may be sharply defined and is produced as denticles in M. majeri. Declivitous face of propodeum convex to flat, longer to shorter than dorsal face. Metanotal groove usually present, forming a weak to strong angle between the mesonotum and propodeum, but is absent or vestigial in a few species. Propodeal spiracle of variable appearance, but always prominent and longer than wide, usually situated at or near propodeal declivity, but nearer to midline of propodeum in some species-groups and in individual species. Petiole. Node always present. In profile, node often squamiform, but may be thicker, e.g., subcuboidal or triangular, and is typically directed posteriad. In full-face view, dorsum of node generally rounded, more rarely angulate, weakly acuminate or indented anteromedially. Petiole with a ventral lobe or keel. Gaster. First tergite vertical and somewhat overarching the petiole in dorsal view, with a small depression for receiving the rear of the node: Legs. Mesotibia and metatibia with one simple spur in most species, spurs reduced or absent in a few groups. General characters. Integument variable, from thick and sculptured to thin, flexible and glossy in very small minor workers of some species, mesonotum may be translucent. Sculpture, where present, predominantly consisting of microreticulation or fine striation, frank rugosity or larger striae found in very few species. Mesopleuron usually with some sculpture, even in otherwise smooth and glossy species. Appressed setae often small, and well-spaced, thick in some species producing pubescence and a silvery sheen in some lights. Erect setae tend to be short and bristly, more rarely fine, long; setae modified and spatulate or even clavate distally in a few species. Many species without erect setae on mesosoma and gaster, or with erect setae confined to margins of gastral tergites. Proventriculus. Proventriculus asepalous.

Major worker

As for minor worker, but differing in the following particulars: Head. Usually planar or weakly concave, but may be strongly concave, never strongly convex. Head often strongly horizontally rectangular, distinctly broader than wide, especially in M. wheeleri species complex. Antennal scapes shorter than in corresponding minor worker, often barely exceeding or not even attaining the posterior margin of the head. Anterior margin of clypeus very variable and may be different to that of corresponding minor worker, often folded or turned back in large-headed species, one major worker with V-shaped anteromedial protuberance projecting anteriad. Mouthparts. Palps, if reduced, as for corresponding minor worker, but may be 3,2 (less than for minor worker) in one species. Otherwise, mouthparts as for corresponding minor worker in many species, but differing significantly in M. wheeleri and M. laticeps species complexes; here, major worker with powerful, truncate, inwardly curved mandibles with four to five teeth in taxa for which major worker is known (likely to be more in unconfirmed major worker of Melophorus species K (TERC)), basal margin folded over horizontally towards buccal cavity to form a planar surface that is delimited partially or fully along its length by a carina. Masticatory margin of mandible vertical, oblique or medially indented. (Characters of mesosoma and metasoma generally as for corresponding minor worker, but dorsal profile of mesosoma may vary, with pronotum and mesonotum generally more raised and convex. Erect setae nearly always present in major worker, even where the corresponding minor worker is glabrous).

Synopsis of Melophorus species

aeneovirens species-group

aeneovirens complex

aeneovirens (Lowne 1865)

=constans Santschi 1928syn n.

=insularis Wheeler 1934syn n.

=iridescens (Emery 1887) syn n.

=iridescensfraudatrix Forel 1915syn n.

=iridescensfroggatti Forel 1902syn n.

attenuipes sp. n.

canus sp. n.

castaneus sp. n.

clypeatus sp. n.

curtus Forel 1902

fulgidus sp. n.

gibbosus sp. n.

griseus sp. n.

kuklos sp. n.

mullewaensis sp. n.

platyceps sp. n.

praesens sp. n.

rufoniger sp. n.

sulconotus sp. n.

tenuis sp. n.

teretinotus sp. n.

bagoti complex

bagoti Lubbock 1883

=Camponotus cowlei Froggatt 1896comb. rev.

gracilipes sp. n.

nemophilus complex

nemophilus sp. n.

anderseni species-group

anderseni Agosti 1998

andersenioides sp. n.

chrysus sp. n.

subulipalpus sp. n.

biroi species-group

biroi complex

argus sp. n.

biroi Forel 1907

=fieldipropinqua Viehmeyer 1925syn. n.

=marius Forel 1910syn. n.

castanopus sp. n.

compactus sp. n.

cuneatus sp. n.

dicyrtos sp. n.

graciliceps sp. n.

gracilis sp. n.

latinotus sp. n.

lissotriches sp. n.

longiceps sp. n.

macrops sp. n.

microreticulatus sp. n.

minimus sp. n.

mjobergi Forel 1915

postlei sp. n.

propebiroi sp. n.

turbineus sp. n.

brevignathus complex

brevignathus sp. n.

marmar sp. n.

quadratus sp. n.

fieldi complex

ankylochaetes sp. n.

bruneus McAreavey 1949

eumorphus sp. n.

fieldi Forel 1910

fulvidus sp. n.

gilliatensis sp. n.

hirsutipes sp. n.

incisus sp. n.

inconspicuus sp. n.

isaiah sp. n.

lanuginosus sp. n.

longipes sp. n.

major Forel 1915 stat. n.

microtriches sp. n.

orthonotus sp. n.

paramorphomenus sp. n.

perthensis Wheeler 1934 stat. n.

sericothrix sp. n.

setosus sp. n.

solitudinis sp. n.

sulla Forel 1910 stat. n.

turneri Forel 1910

=pillipes Santschi 1919syn n.

=turneriaesopus Forel 1910syn. n.

=turnericandidus Santschi 1919syn. n.

vitreus sp. n.

oblongiceps complex

oblongiceps sp. n.

wheeleri complex

brevipalpus sp. n.

caeruleoviolaceus sp. n.

cerasinoniger sp. n.

chauliodon sp. n.

diversus sp. n.

hexidens sp. n.

laticeps Wheeler 1915

parvimolaris sp. n.

pelorocephalus sp. n.

prominens sp. n.

purpureus sp. n.

(‘species K’ [TERC])

wheeleri Forel 1910

=omniparens Forel 1915syn. n.

xouthos sp. n.

fulvihirtus species-group

barbellulatus sp. n.

fulvihirtus Clark 1941

ludius species-group

hirsutus complex

hirsutus Forel 1902

ludius complex

ludius Forel 1902

pusillus sp. n.

translucens sp. n.

majeri species-group

majeri Agosti 1998

potteri species-group

macroschismus sp. n.

pelecygnathus sp. n.

potteri McAreavey 1947

Total: 93 species

Removed from Melophorus

scipioForel 1915 (to Prolasius) comb. rev.

Key to Melophorus species based on workers

The key to species is based on workers, as species-level separation of the other adult castes is not only extremely difficult, but of very limited utility. Moreover, the reproductive castes of the less common species have either not been collected or are often unable to be associated with workers (since most material examined has come from trapping or opportunistic hand collection, rather than from nests). Major and minor workers of a specific Melophorus taxon have been included in the measurements where possible. However, for some uncommon species only minor or major workers are known. (Note. ‘species K’ (TERC) and other Melophorus specimens held in the TERC Collection were not available as loan material except under restrictive conditions that were not acceptable to the authors of this paper.

1 Pronotum surrounded by translucent lamina; metanotal groove obsolete in minor worker, a weak furrow in major worker; torulus pedunculate around antennal insertions; cuticle of mesosoma with dense striolate-microreticulate sculpture (eastern Australian seaboard) (M. ludius species-group) (M. hirsutus species-complex) (Fig. 91(a–h) hirsutus
Pronotum without translucent lamina; if cuticle of mesosoma with dense striolate-microreticulate sculpture, then metanotal groove always present, although it may be reduced to a slight transverse indentation; torulus never pedunculate as above (except in one rare population of M. lanuginosus) 2
2 Large, oblique propodeal spiracle situated well before declivitous face of propodeum, the spiracle bisecting much of the propodeum; mandible modified in two of the three species (either securiform, its masticatory margin with small to minute, blunt, evenly-sized teeth (except for the long, sharp, apical tooth), or edentate); PF reduced (3,4) in two of the three constituent species (M. potteri species-group) 3
Spiracle not as above, generally situated on declivitous face of propodeum; mandible and mandibular teeth not modified as above, teeth usually pointed 5
3 Mandible edentate or with minute crenulations along its masticatory margin; head capsule elongate-rectangular; anterior margin of clypeus straight; PF 3,4 (JDM 1032) (inland areas of least QLD, SA and WA) (Fig. 97a–g) pelecygnathus
Mandible not edentate, mandibular teeth large enough to be easily distinguished; head capsule square, rectangular or oval, if rectangular then anteromedial clypeal margin protrusive; PF 3,4 or 6,4 4
4 PF 3,4; general appearance glossy; head capsule square or rectangular; anterior clypeal margin with square protrusion; basal margin of mandible denticulate; basal margin of mandible expanded distally (widespread) (Fig. 98a–g) potteri
PF 6,4; general appearance matt; head capsule oval; anterior clypeal margin broadly convex but not protrusive; basal margin of mandible not denticulate; basal margin of mandible evenly curved throughout its length (JDM 1082) (inland SW WA) (Fig. 96a–d) macroschismus
5 Propodeum armed with short, acute denticles; pronotum, mesonotum and propodeum flattened and delimited by blunt carinae in minor worker; antennal lobes raised, the sector between them recessed and oval-longitudinal in shape; metatibial apical spur absent (Fig. 95a–g) (M. majeri species-group) majeri
Propodeum always unarmed; mesosoma never carinate as above, usually with rounded surfaces; if antennal lobes raised then sector contained within them triangular or hemispherical; metatibial apical spur well-developed in most groups 6
6 Head and mesosoma extensively covered with short, stout, peg-like bristles; in outline, pronotum and mesonotum flattened; metatibial apical spur stout but very short (M. fulvihirtus species-group) 7
Head and mesosoma not extensively covered with stout, peg-like bristles; pronotum and mesonotum generally sinuous in outline 8
7 Head, body and appendages covered in short, peg-like setae; cuticle strongly matt with coriaceous sculpture; posterior margin of head of all workers broadly concave; mandible of minor worker very finely striate, individual striae invisible under low power magnification (NSW, SA, Vic) (Fig. 90a–g) fulvihirtus
Short peg-like setae much reduced on antennae and absent from legs; cuticle finely shagreenate and weakly shining; posterior margin of head of minor worker planar; mandible of minor worker coarsely striate (very rare, southern WA; SA) (JDM 613) (Fig. 89a–g) barbellulatus
8 Maxillary palp segments short (not reaching neck sclerite), narrow and terminating in a subulate (awl-shaped) segment; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers (except chrysus), and four to six teeth in minor worker (M. anderseni species-group) 9
Maxillary palp of variable length, but often extending beyond neck sclerite and always with lobiform terminal segment; PF < 6,4 where palp segments extremely reduced and difficult to see; metatibial apical spur nearly always present and elongate; in full-face view, masticatory margin of mandible in major worker usually not strongly oblique, but if so, then almost always with at least five teeth; minor workers with ≥ five teeth 12
9 In profile, petiolar node thick and quadrate or broadly rectangular in the minor worker; major worker hairy and rather matt in appearance 10
In profile, petiolar node thickly squamiform in the minor worker; known major worker (M. chrysus) smooth and glossy in appearance 11
10 Anterior clypeal margin broadly convex and protrusive; clypeal psammophore located below midline of clypeus (major worker) or near its anterior margin (minor worker); antennal scape of minor worker devoid of erect setae (northern Australia) (Fig. 26a–h) anderseni
Anterior margin of clypeus weakly convex, clypeus folded back and not protrusive; clypeal psammophore located at midline of clypeus; antennal scape of minor worker with many short, erect, bristly setae (JDM 1105) (mid-west WA; NSW) (Fig. 27a–d) andersenioides
11 In profile, pronotum smoothly rounded and inclined at angle > 30°; head and body strongly shining to glossy, with superficial microreticulation only; in profile, clypeus evenly convex or more strongly convex posteriorly, but not bulbous; yellow; “pillipes” condition (whorls of fine, erect setae on appendages) in some populations (widespread but very rare) (JDM 898) (Fig. 28a–g) chrysus
In profile, pronotum more-or-less flattened, only very weakly inclined anteriad; head and body weakly to moderately shining, the sculpture ranging from superficial microreticulation to evident shagreenation or minutely striate sculpture; in profile, clypeus strongly convex, tending to bulbous (major worker unknown); ochraceous; “pillipes” condition not seen (JDM 1182) (known from three collections only in WA, SA) (Fig. 29a–d) subulipalpus
12 Setae of clypeal psammophore fine and placed at around the midpoint of clypeus; anterior of margin of clypeus a moderately flattened curve in all workers and not covering the base of the mandibles; five to seven mandibular teeth; major worker with same mandibular structure as minor worker; in profile, mesosoma long and gracile, with obliquely descending propodeum (M. aeneovirens species-group (part), [M. nemophilus species-complex]) (Bassian distribution) (one species: M. nemophilus) (JDM 1036) (Fig. 25a–h) nemophilus
If with fine clypeal psammophore set at midpoint of clypeus and number of mandibular teeth more than five, then largest major worker with short, massive, elbowed mandible directed posteriad, mesosoma usually not long and gracile, and declivitous face of propodeum not as above 13
13 In full-face view, anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, the medial clypeal sector often produced so that it is protrusive when seen in profile; psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, propodeum elongate and oblique or broadly rounded (M. aeneovirens species-group [part]) 14
In full-face view, anterior clypeal margin variable, but not covering whole or part of the retracted mandible, the medial clypeal sector not narrowly protrusive, although it may be broadly protuberant; psammophore often placed along the midpoint of the clypeus or even above it; in profile, propodeum typically truncate or narrowly rounded (M. biroi and ludius species-groups) 32
14 In full-face view, psammophore in a row slightly above anterior clypeal margin; anterior margin of clypeus acuminate at its midpoint; metatibia may have more than two rows of preapical spines (M. bagoti complex) 15
In full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines (M. aeneovirens complex) 16
15 Metatibia armed with two rows of preapical spines (JDM 199) (arid and semi-arid WA) (Fig. 24a–g) gracilipes
Metatibia armed with five rows of preapical spines (arid areas; widespread) (Fig. 23a–k) bagoti
16 Main teeth of mandible supplemented with small or indistinct denticles, total number of teeth and denticles ≥ six; in full-face view, head of minor worker indented below the eye, giving a bell-shaped appearance to the head capsule; workers matt, shagreenate, with very many long, flexuous setae over silvery pubescence (widespread but occasional) (JDM 788) (Fig. 8a–g) canus
Teeth of mandible not as above, total number of teeth usually five; head of minor worker (weakly) laterally indented only in Melophorus griseus, which has five distinct mandibular teeth; in full-face view head shape square with rounded posterior angles, rectangular or oval, often with domed posterior margin of head; workers with or without erect setae, where present these usually short and bristly and never long and flexuous 17
17 In profile, head capsule very strongly compressed dorsoventrally, especially in minor worker; maxillary palps short, not reaching neck; in profile, dorsum of mesosoma more-or-less linear after weak anterior pronotal incline, the metanotal groove vestigial in minor worker and weakly impressed in media and major workers; anterior clypeal margin weakly convex; bicoloured; (Bassian distribution) (JDM 787) (Fig. 17a–g) platyceps
In profile, if head capsule very strongly compressed dorsoventrally (M. tenuis), then mesosoma not more-or-less linear, although it may be generally elongate, and maxillary palps longer, reaching to neck sclerite 18
18 In full-face view, eyes of minor worker placed high on head, breaking outline of head capsule where the broadly convex posterior margin of head meets the sides; major and minor worker glabrous, smooth and shining, appressed setae spaced much greater than their own length apart; in profile, major worker with flat mesonotum that overarches the pronotum and; in full-face view, with a protruding, weakly bifurcate anteromedial clypeal margin (two pins, Coward Springs, SA) (Fig. 12a–g) fulgidus
In full-face view, eyes of minor worker generally not breaking outline of head; if eyes of minor worker do break the outline of the head capsule, then eyes placed much lower on head; posterior margin of head generally strongly convex (domed) or more-or-less planar, but if tending to broadly convex, then worker not glabrous, smooth and shining (major worker often similar to the above, but can be distinguished if mesonotum is convex, or, the ant has dense appressed pubescence and/or short, erect setae on the mesosoma, or, anteromedial clypeal margin is not protrusive and bifurcate) 19
19 Minor worker very small (HW ≤ 0.50 mm); metafemur of minor worker of peculiar appearance, being attenuated to the midpoint and thereafter of uniform width to its junction with the tibia (media worker with similar condition, but attenuation more gradual and less conspicuous); head of minor worker rather elongate and very strongly domed; anteromedial sector of clypeus of major worker flattened towards its anterior margin and not extending beyond flanks of clypeus (midwest coast of WA only) (JDM 1102) (Fig. 7a–g) attenuipes
Minor worker larger (HW > 0.50 mm); metafemur of normal appearance, i.e., gradually attenuating towards its junction with the tibia; head of minor worker generally roundly rectangular or square with a domed or planar posterior margin of head; anteromedial section of clypeus of known major workers protrusive to varying degrees and often also projecting when seen in profile 20
20 Tibiae with fine, appressed pubescence in addition to stout, socketed, appressed to subdecumbent setae 21
Tibiae with stout, socketed, appressed to subdecumbent setae only, fine, appressed pubescence lacking 24
21 In profile, minor worker (major worker unknown) with pronotum flattened posteriad and mesonotum also flattened before descending steeply to metanotal groove; minor worker larger (HW ≈ 1.50 mm); bright, light orange with brown gaster (Kimberley region of WA; NT) (Fig. 20a–d) sulconotus
In profile, posterior pronotum and mesonotum of minor worker weakly to strongly convex; minor worker smaller (HW ≤ 0.90 mm); colour variable but not as above 22
22 Antennal scapes and tibiae without bristly erect and semi-erect setae, and short, erect setae normally sparse on dorsum of mesosoma; head of minor worker oval or squared and frontal triangle triangular; in profile, mesosoma of minor worker usually gracile, pronotum and mesonotum forming a gentle curve (non-gracile populations [e.g., Armidale, NSW] also lack bristly erect or semi-erect setae on antennal scapes or tibiae); upper frons of major worker partially shagreenate (very variable morphology, possibly two or more species represented here) (Eastern Australia [mainly]; NT, WA; no SA records) (Fig. 11a–g) curtus
Antennal scapes and tibiae with bristly erect and semi-erect setae normally present on all surfaces, and short, erect setae moderately abundant on dorsum of mesosoma; if bristly erect setae abraded or absent from antennal scapes and tibiae, then head of minor worker bell-shaped in full-face view and frontal triangle narrowly semi-oval (some workers of M. griseus); in profile, pronotum and mesonotum may form a strong convexity; frons of major worker (only known for Melophorus gibbosus) uniformly distinctly microreticulate 23
23 Frontal carinae of minor worker (major worker unknown) raised and laminate at edges; frontal triangle narrowly semi-oval; sides of head concave below eyes, giving it a bell-shaped appearance; in profile, pronotum and mesonotum form a gentle curve (as in Fig.) (Kimberley region, WA) (JDM 948) (Fig. 14a–d) griseus
Frontal carinae of workers not raised or laminate at edges; frontal triangle triangular; sides of head of minor worker not divergent below eyes; in profile, pronotum and mesonotum form a strong convexity (as in Fig. 38) (widespread but uncommon) (JDM 1112) (Fig. 13a–g) gibbosus
24 In profile, mesosoma of minor worker with a compact appearance, its dorsal outline describing a pronounced arc due to shape of the mesonotum and mesopleuron (mesosternal outline and dorsum of mesonotum strongly convergent anteriorly) 25
In profile, mesosoma of minor worker tending to linear in orientation, its dorsal outline straight or describing a weak arc (mesosternal outline and dorsum of mesonotum weakly convergent to subparallel anteriorly) 27
25 Mesonotum and propodeum of minor worker confluent, metanotal groove completely lacking (major worker unknown) (northern WA; NT) (JDM 897) (Fig. 22a–d) teretinotus
Metanotal groove present in minor worker, albeit may be shallow, mesonotum and propodeum clearly separated 26
26 In profile, clypeus distinctly recurved at about midpoint, produced over mandible as small ledge; in full-face view, anterior margin of major and minor worker clypeus a broadly convex, sometimes crenulate curve that does not protrude over apical curve of mandible; in profile, dorsum of minor worker mesosoma moderately arcuate (widespread; common) (Fig. 6a–g) aeneovirens
In profile, clypeus straight or weakly and broadly convex, produced over mandible as a very pronounced ledge; in full-face view, anteromedial margin of major and minor worker clypeus produced as a narrow flange that is distinctly notched or even forked at its midpoint; dorsum of minor worker mesosoma strongly arcuate, almost elliptical (NT, Kimberley region WA) (Fig. 15a–g) kuklos
27 In full-face view, anteromedial margin of clypeus produced as a narrow, rectangular flange with a straight or weakly indented edge (otherwise, anatomically identical with M. praesens) (Pilbara region, WA) (JDM 1242) (Fig. 10a–g) clypeatus
In full-face view, anteromedial margin of clypeus not produced as a narrow, rectangular flange 28
28 Head of minor worker conspicuously dorso-ventrally compressed (seen in profile, head width < 0.5 × head length); anterior clypeal margin evenly convex (northern Kimberley, northern NT) (major worker unknown) tenuis
Head of minor worker not conspicuously dorso-ventrally compressed (seen in profile, head width > 0.5 × head length); anterior clypeal margin with a medial notch or crenulation 29
29 In profile, pronotum of minor worker flattened; in dorsal view, pronotum of minor worker moderately attenuated anteriad; black, very gracile species (one pin only of two damaged minor workers from Mullewa, WA) (Fig. 16a–d) mullewaensis
In profile, pronotum of minor worker convex; in dorsal view, pronotum of minor worker with globose outline, that sclerite not or only very weakly attenuated anteriad 30
30 Major and minor workers with medial sector of clypeus produced broadly as a flange that projects over the basal half of the mandibles; larger species (HW of large major workers ≥ 3 mm); foreparts light tan or orange to dark crimson (never brown), gaster brown (widespread, mainly arid and semi-arid) (JDM 545) (Fig. 19a–j) rufoniger
Major and minor workers with clypeus broadly and gently convex, projecting over base of mandibles only; smaller species (HW of large major workers ≤ 2.3 mm); foreparts mostly brown, but can be black to light reddish-brown 31
31 Minor and media worker with slight medioccipital protuberance (best seen in full-face view with head tilted down slightly); pronotum and gaster of all workers with appressed setae overlapping or at least much closer to neighbouring setae than their own length; in profile, propodeum of minor worker with flattened, elongate dorsum, a barely discernible propodeal angle and often a sharp anterior peak (arid and semi-arid) (JDM 304) (Fig. 18a–g) praesens
Minor and media worker without medioccipital protuberance, posterior margin of head broadly and weakly convex tending to planar when seen In full-face view, pronotum (and, often, gaster) of all worker castes with very short, often inconspicuous appressed setae, these separated from one another by much more than their own length; in profile, propodeum of minor worker without a sharp anterior peak, and commonly with a gently rounded dorsum and weak but discernible propodeal angle (arid and semi-arid) (JDM 1034) (Fig. 9a–g) castaneus
32 Major and minor workers with combination of long mandibles (i.e., apical tooth of retracted mandible reaching to at least the tentorial pit on opposite side of head capsule), similar appearance of head capsule in major and minor workers and short maxillary palps, segments four to six combined barely longer than segment three, in profile, the entire palp reaching only to middle of venter of head capsule in minor worker when head is moderately inclined; head of major worker without short, massive, elbowed mandible directed posteriad; all workers with five mandibular teeth; median sector of clypeus uniformly convex and moderately protuberant, anterior clypeal midpoint a small, blunt angle (oblongiceps complex) (Lake Eyre Basin, SA) (Fig. 75a–g) oblongiceps
Major and minor workers without combination of long mandibles, similar appearance of head in major and minor workers and short palps; if head of major worker similar to that of minor worker, then mandible short (i.e., apical tooth of retracted mandible reaching at most to antennal insertion on opposite side of head) (remaining M. biroi and M. ludius species-group members) 33
33 In full-face view, area around frontal carinae and medial sector of clypeus deeply recessed in major worker, and also in media workers of Melophorus compactus; in major, media and minor workers of one species, torulus (antennal sclerite) produced to form a pronounced and sometimes pedunculate flange that encircles the base of the antennal scape; psammophore generally placed on or just above anterior margin of clypeus; minor workers hairy with thick, longish, unmodified erect setae (pedunculate torulus present; clypeal psammophore placed at midpoint) or with bristly, short erect setae (pedunculate torulus absent; clypeal psammophore placed at or just above anterior clypeal margin) 34
In full-face view in major and media worker, area around frontal carinae and medial sector not noticeably recessed and torulus not expanded and pedunculated, torulus inconspicuous in all subcastes; most minor workers without the combination of anteriorly placed psammophore and hairiness with bristly, unmodified erect setae (minor workers of M. sericothrix may key out here as they are hairy with bristly setae, but these setae are longer, i.e., diameter of eye ≥, whereas, in M. mjobergi and M. postlei the bristly, erect setae are much shorter, i.e., diameter of eye <<) 37
34 Midline of head capsule between frontal carinae with a short, vertical flange in major and media workers; clypeal psammophore placed at around midpoint of clypeus; workers with thatch-like distribution of long white setae on pronotum, erect setae on mesosoma tend to be coarse and relatively long (one rare population from Pilbara region, WA) (JDM 472 (pt)) lanuginosus
Midline of head capsule between frontal carinae without a short flange in major and media workers; clypeal psammophore placed on or just above anterior border of clypeus; workers with short, bristly, erect, unmodified setae on head, body and antennal scape (biroi complex (pt)) 35
35 Head of major worker without distinct sculpture, strongly shining, setae-bearing sockets on head (if visible) appearing as tiny pits only, sculpture also reduced on head of media worker, which is moderately shining; in full-face view, antennal carina of major worker distinctly extended posteriad past antennal insertion, posterior extension of carina straight; eye of minor worker placed medially on head capsule and large in size (in profile, eye length ≈ 0.40× length of side of head capsule) (Eastern Australia) (Fig. 33a–g) compactus
Head of all workers microreticulate and moderately shining to matt, setae-bearing sockets on head of major worker impressed so as to appear as small, oval depressions; in full-face view, antennal carina of major worker limited to flange around antennal insertion, weak ridge representing posterior extension of carina strongly concave posteriad; eye of minor worker placed anteriorly on head capsule and moderate in size (in profile, eye length ≈ 0.25× length of side of head capsule) 36
36 Appressed setae in all workers fine and forming pubescence that largely obscures underlying cuticle, which is matt in appearance (northern Australia) (JDM 485) (Fig. 44a–g) postlei
Appressed setae in all workers loose and relatively thick and not obscuring underlying cuticle, which is moderately shining in appearance (northern Australia, apparently sympatric with above species) (JDM 899) (Fig. 43a–g) mjobergi
37 Gaster with curved erect setae, semi-erect setae and a few decumbent setae only, genuine appressed setae lacking; body generally strongly sculptured and hirsute, antennal scapes and legs with whorls of many fine, straight setae (several hairy members of the M. fieldi complex) 38
Gaster with at least well-spaced appressed setae between the longer, erect or semi-erect pilosity if ant has hairy legs and scape 40
38 Mesonotum and propodeum globose, mesonotum, mesopleuron and propodeum separated from each other by a deep sulcus (WA, NT) (JDM 945) (Fig. 58a–g) incisus
Mesonotum and propodeum not globose; mesonotum separated from mesopleuron and propodeum by weak groove or indentation 39
39 In profile, petiolar node of major and media workers narrow, squamiform, scale-like in appearance; (petiolar node of minor worker not so distinctive, but ant can be distinguished by more shining appearance of head and anterior mesosoma and the rounded propodeum); head of major worker shining in appearance (widespread arid and semi-arid) (JDM 1070) (Fig. 52a–g) ankylochaetes
In profile, petiolar node of media and minor worker a low, rounded tubercle, that of major worker erect and not narrowly squamiform or scale-like in appearance; minor worker matt or with dull sheen only and with broadly truncate propodeum; head of major worker distinctly matt and may be rugulose (widespread, abundant) (JDM 532) (Fig. 58(g)-(k),(l)) hirsutipes (part)
40 Small (HW of small minor workers 0.50 mm ≤, HW of known major workers ≤ 0.80 mm) species; weakly sculptured overall, with cuticle of mesosoma visibly thin, the mesonotum translucent to varying degrees; mesopleuron either smooth or with vestigial sculpture only (nb. taxa in couplet 40 are members of the M. ludius complex) 41
Usually larger species but if small, then cuticle of mesosoma thick and opaque (including the mesonotum), and mesopleuron generally with pronounced microreticulate or other impressed sculpture. (Melophorus ludius minor workers may be confused with minor workers of the following two taxa but can be distinguished from them by virtue of the combination of a moderate-sized eye and truncate [but not elongate] propodeum. In this case, however, the mesosoma is opaque though glossy.) 42
41 In profile, propodeum of all worker castes narrow and obliquely elongate, with a declivitous face that descends at an angle near 45°, minor worker propodeal spiracle elongate (≥ 0.67× length of propodeum, measured along the spiracle); eye moderate-sized (EL 0.12-0.15; EI 20-36); (southwest WA) (JDM 500) (Fig. 94a–g) translucens
In profile, propodeum of all worker castes not narrow and obliquely elongate as above; minor worker propodeal spiracle shorter (≤ 0.50 length of propodeum, measured dorsoventrally); eye generally larger (EL 0.15–0.21; EI 31-40) (mainland Australia; arid) (JDM 1235) (Fig. 93a–g) pusillus
42 In profile, head of minor worker weakly to moderately dorsoventrally compressed; in profile, eye set above midpoint of gena; clypeal psammophore set at around midpoint of clypeus to halfway between midpoint and anterior margin (major worker) and below midpoint to just above anterior margin (media and minor worker); head, body and legs of minor worker strongly pubescent, all workers with many short, unmodified, prickly, erect setae on head and body with from a couple to a moderate number distributed along antennal scapes, but such setae mainly or wholly absent from tibiae; propodeum with obliquely declivitous face; major worker with several preapical metatibial spines (Bassian distribution; SA and WA) (JDM 617) (Fig. 69a–g) sericothrix
If minor and major worker similar in profile to the above and generally pubescent, then at least some short, erect setae modified (spatulate or thickened distally) 43
43 Minor and major workers worker clothed with fine, appressed silvery setae that form pubescence in minor worker, at least, in conjunction with multiple scattered, modified erect setae (modified setae varying from distally slightly flattened to clavate) on head, mesosoma and gaster (ants in couplets 43–57 belong to the M. biroi complex, (pt), except for M. ludius) 44
Minor and major workers not clothed with both fine, appressed silvery setae and multiple scattered, modified erect setae (either of these conditions may be individually present) 45
44 In full-face view, eye of minor worker moderately convex, bulging well beyond outline of head capsule; in profile, mesosoma of minor worker sinuous, the mesonotum dipping towards its junction with the propodeum, forming a weak v-shaped notch; frontal carinae of major worker straight or weakly convex, cuticle of major worker head matt or weakly shining and minutely pitted (widespread; arid) (JDM 1121) (Fig. 39a–g) lissotriches
In full-face view, eye of minor worker only weakly convex, barely interrupting outline of head capsule; in profile, pronotum of minor worker rising gently, and mesosoma thereafter more-or-less straight, the mesonotum not dipping towards the propodeum, the metanotal groove not demarcated by a v-shaped notch; frontal carinae of major worker concave, cuticle of major worker head smooth and shining (mainly southern Australia; arid and semi-arid) (JDM 784) (Fig. 36a–g) graciliceps
45 Metatibia of major worker with only one preapical spur; clypeal psammophore placed anteriorly, at or just above anterior margin of clypeus in minor worker and often in major worker; legs compact; head in profile dorsoventrally compressed in minor worker of many taxa, with eyes placed high on sides; mainly smaller species (HW of smallest minor 0.36 mm, average HW of smallest minors 0.46 mm; HW of largest known major 1.29 mm, average HW of largest majors (where known) 1.05 mm) 46
Metatibia of major worker and often minor worker with two or more preapical spurs; clypeal psammophore usually placed just below to above centrepoint of clypeus (caution: clypeus may be folded back giving appearance of anterior margin); legs often spindly with elongate metatibia in minor worker; head in profile usually ovate, rarely visibly dorsoventrally compressed; mainly larger species (HW of smallest minor 0.43 mm, average HW of smallest minors 0.77 mm; HW of largest known major 3.57 mm, average HW of largest majors (where known) 1.85 mm) 59
46 In profile, propodeal dorsum of minor and media workers extremely narrow and almost acuminate; metanotal groove in all workers narrowly and deeply impressed; mesonotum of minor worker hypertrophied so that metathoracic spiracle is situated on its underside in a distinctly lateral position; all workers with weak pubescence and a moderate number of erect setae on mesosoma (southwest WA) (JDM 230) (Fig. 34a–g) cuneatus
Propodeal dorsum of minor and media workers mostly moderately truncate, but if narrow then metanotal groove v-shaped; mesonotum of minor worker not hypertrophied as above, the metathoracic spiracle situated on dorsum of ant or nearly so; workers without weak pubescence (except in minor worker of Melophorus propebiroi) 47
47 Minor worker with relatively long, partially overlapping appressed setae that form a weak pubescence on mesosoma and gaster; short, bristly, erect mesosomal setae present and plentiful (major worker unknown; southwest WA) (JDM 1221) (Fig. 46a–d) propebiroi
Minor worker with short, non-overlapping appressed setae on mesosoma and gaster that do not form pubescence; short, bristly, erect mesosomal setae sparse or absent in minor worker 48
48 Profile of minor worker (major worker unknown) bimodal, with smooth, glabrous, rounded pronotum and propodeum, and scalloped mesopleuron; petiolar node thickly squamiform, almost tubercular (Torresian, in the far north) (Fig. 30a–d) argus
Profile of minor worker not as above, specifically never bimodal and glabrous with a smooth rounded propodeum; propodeum most commonly truncate to varying degrees and propodeal angle may be raised; petiolar node more narrowly squamiform, and may strongly flattened, especially in the major and media workers 49
49 In profile, head of minor worker distinctly dorsoventrally flattened; in full-face view, head of minor worker extremely narrow, CI ≤ 75 (Lake Mere, NSW only, major worker unknown) (Fig. 40a–d) longiceps
In full-face view, if head of minor worker dorsoventrally flattened, then distinctly broader, CI ≥ 85 50
50 Minor worker (major worker unknown) with propodeum produced vertically and conical in profile; propodeal spiracle very large, approximately 0.75× height of propodeum; eye larger (eye length approximately 0.40× length of side of head capsule) (two pins, Gawler Ra., SA) (Fig. 47a–d) turbineus
Propodeum of minor worker not produced vertically except in M. dicyrtos, not conical in profile; propodeal spiracle shorter (≤ 0.60× height of propodeum) 51
51 Head and mesosoma of minor worker strongly matt, dull, with uniform, minute, net-like microreticulation; a transverse row of short, stout unmodified setae placed across centre of pronotum; in profile, propodeum weakly rounded or forming a slight angle between dorsal and declivitous faces (major worker unknown: known only from Eneabba region and Yanchep NP, WA) (JDM 1180) (Fig. 38a–d) latinotus
Head and mesosoma of minor worker with moderate to strong sheen and without transverse row of short, erect pronotal setae as described above; microreticulate sculpture, where present, mainly confined to mesopleuron, except in M. microreticulatus 52
52 In full-face view, major worker with posterior clypeal margin not arched or falling away between antennal insertion and tentorial pit; anterior clypeal margin straight and not protuberant; in profile, major worker mesosoma elongate, smoothly bimodal; first gastral tergite of both major and minor worker with line of erect marginal setae and with other erect setae present, and workers very small (major worker HW ≤ 0.65 mm, minor worker HW ≤ 0.40 mm); minor worker with a pair or several long, erect setae at midpoint of pronotum; major and minor worker mesosoma glossy, with superficial sculpture only (northern WA only) (Fig. 37a–g) gracilis
In full-face view, major worker often with posterior clypeal margin arched and falling away between antennal insertion and tentorial pit; anterior clypeal margin usually weakly convex, protuberant or with anteromedial dimple indicated; if major worker with posterior clypeal margin not arched or falling away between antennal insertion and tentorial pit and with glossy, unsculptured appearance (M. ludius), then profile compact with raised mesonotum and narrow, rounded propodeum; if minor worker small and with glossy, unsculptured mesosoma, then usually glabrous and always without erect marginal setae on first gastral tergite 53
53 In profile, propodeum of minor and major worker protuberant and strongly truncate, with elevated dorsal surface which is much shorter than declivitous surface; larger ants (HW of minor worker 0.65 mm ≥, HW of major worker 1.25 mm ≥); metanotal groove characteristically a deep V-shaped notch; most workers with long, flexuous setae but these may be short and bristly (northern NT, QLD and WA) (JDM 470) (Fig. 35a–g) dicyrtos
In profile, propodeum of minor and major worker not of above appearance, propodeum either rounded or truncate, but if truncate then not narrowly produced with elevated dorsal surface; minor worker much smaller (HW 0.50 mm ≤) and known major workers usually smaller, except for M. castanopus; metanotal groove of minor worker usually weakly impressed (see figure below); minor workers often glabrous or nearly so 54
54 Eye large (EI 40-41); mesosoma with at least several erect setae, including propodeal setae; In profile, metanotal groove of minor worker deeply impressed and propodeum rounded into its declivitous face; first gastral tergite with erect setae, including a line of marginal setae; (major worker unknown) (v. rare; NSW and QLD) (Fig. 41a–d) macrops
Without combination of large eye and erect marginal setae on first gastral tergite; in profile, metanotal groove of minor worker usually weakly impressed and propodeum usually more-or-less truncate, descending into its declivitous face through an angle; minor worker usually glabrous, though may have one or two erect setae on pronotum 55
55 Minor worker with combination of large eye (EI 40 ≥), small size (HW 0.40 mm ≥), lack of erect setae on mesosoma and first gastral tergite and distinct microreticulate sculpture over mesosoma (may be weaker on pronotum in some specimens); major worker with posterior clypeal margin not arched or falling away between antennal insertion and tentorial pit; anterior clypeal margin straight and not protuberant; major worker pronotum tending to bulbous and in profile breaking the mesosoma outline by protruding above the mesonotum; mesosomal sculpture as for minor worker (southern mainland Australia; arid and semi-arid) (JDM 792) (Fig. 42a–g) microreticulatus
Minor worker without combination of large eye, small size and distinct microreticulate sculpture over mesonotum; erect marginal setae may be present; if major worker with clypeal conformation as above, then major worker mesosoma glossy and unsculptured or with vestigial microreticulation on mesopleuron and propodeum only, and pronotum does not protrude above the mesosomal outline when seen in profile 56
56 Smaller species (minor worker HW 0.40 mm ≤, largest major worker HW 1.05 mm ≤); in profile, minor worker head ovate without distinct dorsoventral flattening; major worker with posterior clypeal margin not arched or falling away between antennal insertion and tentorial pit; anterior clypeal margin straight and not protuberant 57
Larger species (minor worker HW 0.47 mm ≥, largest major worker HW 1.10 mm ≥); in profile, minor worker head weakly to strongly dorso-ventrally flattened, with eye placed high on side; major worker with posterior clypeal margin arched, falling away between antennal insertion and tentorial pit; anterior clypeal margin convex, protuberant and may be dimpled 58
57 In profile, minor worker propodeum weakly truncate or rounded, descending into its declivitous face at an angle of about forty-five degrees; minor worker eye moderate (EI 19-30); minor worker antennal scape longer (SI to 120); mesosoma and first gastral tergite occasionally with one or a couple of erect setae in eastern populations; major worker morphologically similar to the following, but larger (HW of measured major worker 1.05 mm) (widespread) (Fig. 92a–g) ludius
In profile, minor worker propodeum strongly truncate and cuboidal, descending into its declivitous face at an angle approaching ninety degrees; minor worker eye large (EI 40-41); minor worker antennal scape shorter (SI as little as 94); mesosoma and first gastral tergite always glabrous; major worker similar to the above but minute (HW of measured major worker 0.47 mm) (arid QLD, SA and WA) (JDM 1220) (Fig. 43a–g) minimus
58 Minor worker with erect setae on first gastral tergite, including a line of marginal setae; mesosoma also with a couple to a few, usually stout erect setae (several specimens may need to be seen because of abrasion), these setae rarely abundant and modified (one series, Pymble, NSW); in profile, pronotum, mesonotum and propodeum in all worker castes flattened and on same plane (NSW, SA, TAS and VIC) (Fig. 32a–g) castanopus
Minor worker lacking erect setae on first gastral tergite; mesosoma also glabrous in minor worker; in profile, pronotum and mesonotum of minor worker tending to be rounded; mesosoma of major worker compact and rounded (similar to M. ludius); propodeum truncate (in which case it is below level of mesonotum) or rounded, the dorsal face much shorter than the declivitous face (widespread, abundant, possible species complex) (Fig. 31a–m) biroi
59 In full-face view, head capsules of major, media and minor workers square with small, flattened eyes, except in media and minor workers of M. marmar, which have a large, convex eye (flattened in the major worker); in profile, eyes placed anteriad of midline of head capsule; anterior margin of clypeus distinctly sinuate, projecting anteromedially as a bluntly triangular extension or flattened dimple in major and media workers; five-toothed mandible of all workers very narrow, parallel and coarsely striate throughout its length; maxillary palps in all workers short, barely attaining neck sclerite at their greatest extremity and often only reaching midpoint of venter of head capsule when head is moderately inclined (M. brevignathus complex) 60
In full-face view, head capsule of major, media and minor workers differing in various respects from the above, which may include width and size of eyes, shape of head and conformation of clypeus and mandibles; in profile, eyes generally placed around midline of head capsule; if mandibles narrow, then elbowed, massive and directed posteriad in large major worker and often finely striate in minor and media worker; maxillary palps variable, may be long, reaching mesopleuron in small minor worker when head is moderately inclined 62
60 In full-face view, eye placed very high on capsule, and slightly above imaginary horizontal line separating head capsule (excluding mandibles) into equal upper and lower sectors; workers glabrous (NSW; NT, inland SA) (Fig. 50a–g) quadratus
In full-face view, eye placed lower on head capsule, its bottom third intersected by an imaginary horizontal line separating head capsule (excluding mandibles) into equal upper and lower sectors; major and media worker, at least, with some erect pilosity on mesosoma, mesosoma of major and media worker may be relatively hirsute 61
61 In full-face view, sides of head capsule straight or even weakly concave anteriad, slightly divergent towards posterior margins of head; frontal carinae shorter and parallel, approximately 0.25× as long again as the vertical height of the frontal triangle; appressed setae on first gastral sclerite longer, separated from preceding and succeeding rows by ≤ 1× their own length; eyes of minor and media workers large and convex (inland SA; WA) (Fig. 49a–h) marmar
In full-face view, sides of head capsule distinctly convex; frontal carinae longer, divergent posteriad, approximately 0.50× as long again as the vertical height of the frontal triangle; appressed setae on first gastral tergite shorter, separated from preceding and succeeding rows by at least 2× their own length; eyes of minor worker similar to those of major worker (NT, southern QLD) (Fig. 48a–g) brevignathus
62 Minor and major worker with five mandibular teeth; major worker with similar mandible to minor worker, not massive, elbowed and directed posteriad; in profile, maxillary palps long, at least in minor worker, attaining mesopleuron when head of ant moderately inclined; in full-face view, anterior margin of clypeus in all workers usually weakly and evenly convex, commonly with anteromedial dimple or weak protuberance (M. fieldi complex) 63
Minor worker often with more than five teeth (up to 15), largest major worker with short, massive, elbowed mandible directed posteriad; in profile, maxillary palps shorter in major and generally in minor workers, in minor worker, when head of ant moderately inclined, only attaining neck sclerite at their maximum extent in most species; in full-face view, anterior margin of clypeus in large major worker usually planar or weakly concave, other subcastes variable but planar or narrowly protuberant anterior clypeal margins predominate (M. wheeleri complex) 87
63 Worker thorax with metanotum apparently developed and confluent with mesonotum, often extending over the propodeum; metanotal suture obsolete, its position indicated only by a superficial, transverse furrow (more pronounced in major worker); propodeum reduced in size and wedge-shaped, with narrow end of wedge often under fold of metanotum; metathoracic spiracle lateral and situated within metanotal sector (NT; WA) (JDM 1063) (Fig. 67a–g) paramorphomenus
Worker thorax of normal appearance, with metathoracic spiracle situated on or near dorsum of mesosoma 64
64 Major, media and minor worker uniformly microreticulate, in profile, petiolar node of minor and media thick and tuberculate in shape, that of major worker squamiform; tibial apical spur absent; mesosoma of minor and media workers matt, glabrous, that of major worker with ≈ 12 short, bristly, erect setae (minor and media workers orange, major worker orange with brown gaster) (NT, QLD, northern WA; arid; rare) (JDM 970) (Fig. 56a–g) fulvidus
Appearance not as above: specifically, if orange with thick petiolar node, then appearance not uniformly microreticulate, and erect setae, most commonly flexuous, present on mesosoma of all workers; tibial apical spur present 65
65 At least lower metafemur (shown here) and all of metatibia with whorls of erect setae directed at 45–90° to surface 66
Metafemur and metatibia without whorls of erect setae directed at 45-90° to surface of extremity, pilosity usually restricted to appressed or subdecumbent setae (where erect setae present, these confined to two or three lines of setae, more commonly several individual setae) 70
66 Tibiae and antennal scape matt, strongly microreticulate; erect setae on metatibia shorter, stout, length of longest setae < greatest width of tibia; appressed metatibial setae thickly distributed and often forming a distinct pubescence, metatibia matt; gaster of minor worker strongly pubescent (common and widespread) (JDM 520) (Fig. 65a–g) microtriches
Tibiae and antennal scape moderately to strongly shining and smooth or with superficial microreticulation; erect setae on metatibia longer, fine, length of longest setae ≥ greatest width of tibia; appressed metatibial setae not conspicuous, metatibia shining; gaster of minor worker usually without long, overlapping appressed setae that form pubescence 67
67 Mesopleuron smooth and shining in minor and media worker at least, ant very glossy; HW of small minor 0.65 mm ≤ 68
Mesopleuron with at least superficial sculpturing in all workers, ant often shining, but not glossy overall; HW of small minor usually 0.65 mm > 69
68 Ant gracile, with outline of mesosternum parallel to outline of mesonotum; in profile, outline of clypeus distinctly protuberant; in profile, petiolar node lower (» 1.2× as high as wide) (major worker unknown) (NT, QLD, WA; arid) (JDM 699) (Fig. 74a–d) vitreus (‘ pillipes ’)
Ant compact, with outline of mesosternum strongly anteriorly convergent to outline of mesonotum; in profile, outline of clypeus weakly convex; in profile, petiolar node higher (» 1.4× as high as wide) (this form mainly Eastern Australian) (Fig. 73m–r, y) turneri (‘ pillipes ’)
69 Anteromedial dimple prominent and protruding as a V-shaped lip; gaster and usually pronotum (at least) with overlapping long, appressed setae that form a silvery thatch in between long, curved, erect setae (arid Australia) (JDM 472) (Fig. 62a–g) lanuginosus (‘ pillipes ’)
Anteromedial dimple weakly developed or vestigial and not protruding as a V-shaped lip; appressed setae between long, curved, erect setae shorter and not forming a silvery thatch (widespread) (Fig. 58a–f, l) hirsutipes (part) (“pillipes”)
70 With combination of: (1) eye relatively large (eye length 0.50× length of side of head capsule in minor worker, approximately 0.33× length of side of head capsule in major worker ≥), (2) in full-face view, periphery of upper frons surrounded to about the level of the eyes with short, bristly, erect setae that are often flattened distally; (3) minor worker small (HW ≈ 0.56–0.59 mm); (4) non-iridescent head of major worker relatively smooth and gleaming (e.g., Fig. 54a) and, (5) clypeal psammophore of fine setae placed at or about midpoint of clypeus 71
Without this combination of characters: specifically, if with relatively large eye and modified setae on the periphery of the frons, then minor worker larger (HW > 0.73mm) and major worker head with fine microreticulation and pitting or iridescent (e.g., Fig. 60a); in other cases setae on frons long and unmodified, and may be lacking entirely 72
71 Minor worker concolorous blackish-brown, finely shagreenate with a dull silky sheen; in profile, pronotum rises gradually to its junction with mesonotum without any obvious convexity, while mesonotum is slightly humped; mesosoma with a few to many short, straight, bristly setae, these often expanded distally, length of longest setae ≤ greatest length of antennal scape; appressed setae short, inconspicuous; major worker and media worker concolorous brown (orange-yellow with brown gaster in holotype), with scattered short, sometimes modified setae; appressed setae on gaster well-separated and do not overlap (mainly semi-arid) (Fig. 55a–g) fieldi
Minor worker variable shades of brown or dark reddish-brown but not blackish-brown with dull, silky sheen; in profile, pronotum smoothly convex, mesonotum completes the curve without a median hump; erect setae on mesosoma often numerous and flexuous, length of longer setae ≥ greatest width of antennal scape (in relatively glabrous minor workers, appressed setae on mesosoma long and conspicuously pale); major worker similar to the above, but short, sometimes modified setae are far more numerous and give a shaggy appearance to most major workers; appressed setae on gaster longer and overlap (mainly semi-arid) (Fig. 53a–g) bruneus (part)
72 Body of major and minor worker clothed with modified, erect setae (distally thickened, clavate or spatulate) to various degrees in addition to unmodified setae; frontal carinae straight or weakly convex 73
True modified, erect setae absent from body of major and minor worker (although some erect setae may be thick and short); frontal carinae divergent posteriad 74
73 In full-face view, sculpture of major and minor worker head matt with microreticulate sculpture; frontal carinae weakly divergent posteriad; appressed setae on appendages sparse, thick and mostly separated from each other by more than their own length (inland WA) (JDM 1247) (Fig. 71a–g) solitudinis
In full-face view, sculpture of major and minor worker head pitted and weakly gleaming with superficial microreticulation; appressed setae on appendages abundant and fine, individual setae strongly overlapping (northern inland areas; rare) (JDM 618) (Fig. 70a–g) setosus
74 Pale yellow, depigmented ants; in full-face view often with clypeus, genae and mandibles paler than frons; mesosoma very often glabrous (widespread, arid and semi-arid) (Fig. 72a–g) sulla (sensu stricto)
Ants darker or bicoloured, often with some erect pilosity on mesosoma 75
75 In profile, pronotum smoothly rounded and mesonotum elongate and broadly convex and strongly developed in all workers, so that pronotum and mesonotum combine to form a near semi-circle; minor worker with truncate propodeum with a protuberant dorsum that usually rises above metanotal groove; colour of minor worker uniformly brown or brown with slightly darker gaster, major worker brown or orange-brown with dark brown gaster (widespread and abundant) (Fig. 68a–g) perthensis Wheeler
In profile, mesonotal outline not as above, if mesonotum strongly convex then pronotum with flattened dorsum and/or mesonotum not elongate; propodeal dorsum of minor worker usually planar or weakly convex though may be high; colour variable, but often with gaster much darker than foreparts in minor worker 76
76 In profile, major and media worker with smooth, elongate propodeum, propodeal angle indicated by only a faint curve; metanotal groove a weak impression so that mesonotal and propodeal outline is barely interrupted; mesonotum and mesopleuron not separated by impression or suture; mesosternal outline strongly convergent anteriad with outline of mesonotum (media and major workers only known; bicoloured orange-and-dark-brown ants) (a few pins, Pilbara region, WA) (JDM 1161) (Fig. 66a–d) orthonotus
In profile, propodeum of major and minor worker not elongate as above, and usually with at least a rounded propodeal angle; metanotal groove distinct and mesonotum and propodeum not nearly confluent as above; mesonotum and mesopleuron indicated by distinct impression if not a suture; mesosternal outline usually more-or-less parallel with outline of mesonotum 77
77 In full-face view, eye of all workers placed very high on capsule, and slightly above imaginary horizontal line separating head capsule (excluding mandibles) into equal upper and lower sectors; workers reddish-brown with pale tibiae and distal femur (WA, SA and NT) (JDM 1246) (Fig. 61a–g) isaiah
In full-face view, eye placed lower on head capsule, at least its bottom eighth intersected by an imaginary horizontal line separating head capsule (excluding mandibles) into equal upper and lower sectors 78
78 In profile, clypeal psammophore in minor worker placed just behind anterior clypeal margin and well below midpoint of clypeus in major worker; eye in most specimens large (eye length 0.20 to 0.25 × length of side of head capsule in major worker, 0.33 to 0.50 × length of side of head capsule in minor worker); propodeum in major worker narrow with an oblique dorsal face; shining brown with gaster slightly darker (NSW, WA) (Fig. 64a–g) major
In profile, clypeal psammophore placed just below midpoint to above midpoint of clypeus; eye variable but often smaller 79
79 Clypeus folded back abruptly slightly below its midpoint, so that anterior portion projects as a protuberance at about 90° to mandible; clypeal psammophore placed along line of demarcation (rare, localised; QLD) (Fig. 57a–g) gilliatensis
Clypeus generally rounded or flattened towards its anterior margin, not abruptly folded back as above 80
80 Appressed setae on the gaster in all workers very small and inconspicuous when gaster is moderately distended, separated from one another by at least their own length, these appressed setae also inconspicuous on mesosoma and never long and silvery; mesosoma glabrous in minor worker or with one or a few flexuous, erect setae; node of minor worker often squamiform; most commonly cuticle shining or even glossy with vestigial or weak shagreenation 81
Appressed setae on gaster of all workers longer and overlapping when gaster is moderately distended, and may form a silvery thatch, appressed setae on mesosoma also overlapping and may be long and cross-linked forming a silvery thatch; mesosoma most frequently with numerous setae, if these sparse then often shorter and stout; node of minor worker characteristically not squamiform, and may be bent distally; most commonly cuticle distinctly shagreenate with weak to moderate sheen 84
81 Minor worker very small (HW < 0.55 mm); frons of head capsule smooth and shining; eye large (eye length approximately 0.40 × length of head capsule); mesopleuron with distinct, wrinkled or scalloped sculpture that may extend to the mesonotum; propodeum a rounded cube; major worker also very small (HW ≤ 0.73 mm) with large eye (eye length approximately 0.38 × length of head capsule); mesopleural sculpture as for minor worker (JDM 786) (Bassian, inland) (Fig. 54a–g) eumorphus
Ant larger (minor worker HW 0.57 mm ≥; known major workers HW > 1.50 mm); if minor worker smooth and shining and generally similar (smallest minor workers of M. vitreus) then mesopleuron smooth and unsculptured or with very superficial microreticulate pattern 82
82 In profile, minor worker gracile, with short, thick petiolar node terminating in a smoothly rounded vertex; clypeus rounded and somewhat protuberant (see Fig. 74); eye very large (eye length ≥ 0.50 × length of side of head capsule); cuticle extremely glossy, with mesopleuron completely smooth or with very superficial microreticulate pattern (sp. JDM 699) vitreus (sensu stricto)
In profile, minor worker less gracile with generally squamiform node that is often inclined at its vertex; clypeus weakly protuberant and usually with distinct dimple at its midpoint (see fig); eye moderate to large (eye length 0.20–0.49× length of side of head capsule); cuticle less glossy tending to matt in some populations, with mesopleuron weakly shagreenate or microreticulate 83
83 Metafemur of minor worker shorter and stouter (0.75 × length of mesosoma ≤); in profile, propodeum generally with a weak to strong angle between dorsal and declivitous surfaces; major worker difficult to distinguish from that of M. longipes, but mesonotum generally moderately convex in profile and metafemur uniformly pale brown ochre to yellowish; tibia same colour as femur (variation across populations and molecular data suggest the possible presence of one or more cryptic species, but these cannot be defined morphologically) (widespread, abundant) (Fig. 73a–l, s–y) turneri Forel (sensu stricto)
Metafemur of minor worker longer and attenuated towards its junction with tibia (0.90 × length of mesosoma); in profile, dorsum of propodeum smoothly curved on to its declivitous face; mesonotum of major worker flat to weakly convex and metafemur increasingly depigmented towards its articulation with the tibia, and the tibia depigmented yellowish-white (NT, SA, WA) (JDM 474) (Fig. 63a–g) longipes
84 Mesosoma glabrous; in full-face view, head strongly microreticulate, matt; eye relatively large (EI ≈ 41), appressed setae on gaster elongate and pale bruneus (minor workers in some populations)
Mesosoma nearly always with some erect setae (usually abundant), where lacking (a few minor workers of M. inconspicuus) eye smaller (EI ≤ 37) and, in full-face view, head always with some sheen 85
85 Mesosoma with erect setae long, flexuous and curved (pronotal setae and those on anterior mesosoma curved posteriad, setae on posterior mesonotum curved anteriad, those on propodeum also curved in both directions); appressed setae on mesonotum and gaster rather long but not combining to form a silvery pubescence; in profile, anterior two-thirds of clypeus often straight or slightly concave, forming an oblique surface, the anteromedial clypeal dimple weak or vestigial; in profile, petiolar node in minor worker thick, to about 0.7× as wide as high, and its dorsum may be noticeably directed posteriad, especially in minor worker (JDM 532) (similar to Fig. 58a–f, l) hirsutipes (part)
Erect mesosomal setae (where present) not long and flexuous, though they may be curved, however, these setae are frequently stout and bristly; appressed setae on mesonotum and gaster may be long and silvery in appearance forming a thick, thatch-like pubescence; in profile, clypeus evenly convex or weakly concave in its anterior third, but not as above; petiolar node thinner, much less than 0.7× as wide as high and either straight or weakly bent posteriad 86
86 Appressed setae on mesosoma and gaster long, forming a coarse, silvery pubescence; erect setae on mesosoma longer (longer setae > diameter of eye); cuticle with strong shagreenate sculpture, matt or with weak sheen; petiolar node in minor worker thicker, to about 0.6× as wide as high, also not a true scale in major worker; ‘pillipes’ condition present in some populations (see above) (JDM 472) (Fig. 62a–g) lanuginosus (part)
Appressed setae on mesosoma and gaster shorter, silvery pubescence limited to small areas of the pronotum or entirely absent; erect setae on mesosoma generally fewer and more bristly in appearance (often < diameter of eye) and entire mesosoma may be glabrous; cuticle generally with weak shagreenate sculpture, except for mesopleuron, and foreparts commonly moderately shining; petiolar node in minor worker essentially squamiform, that of major worker a true scale; ‘pillipes’ condition always absent (widespread, abundant) (JDM 28) (Fig. 60a–g) inconspicuus
87 Minor worker mandible with 15 or more sharp teeth (major worker not inspected) (Victoria River district, NT (Andersen 2007)) species K’ (TERC)
Minor worker with nine teeth ≤ 88
88 Anterior margin of clypeus in major and media workers a prominent rim that is produced anteromedially as a broadly angulate projection, this projection directed anteriad at angle of about 90° to head capsule when seen in profile; mandible of major worker usually with three distinct teeth (fourth tooth reduced to an angle in most cases); mandible of minor workers minutely striate with six or more teeth on masticatory margin (mid- and north-west WA) (JDM 1244) (Fig. 85a–g) prominens
If mandible of minor worker minutely striate with six or more teeth on masticatory margin, then major and media workers without above clypeal configuration (in similar species, anteromedial clypeal projection is directed ventrally); major worker with four or five teeth. 89
89 Palps extremely short and variable in appearance and number of segments, palps when directed posteriad not reaching the hypostomal border, PF 4,3 or 3,3 or even apparently 2,3 (in undissected major worker) (interior SA) (Fig. 76a–h) brevipalpus
Palps longer, extending beyond hypostomal border and PF always 6,4 90
90 Colour pale, depigmented yellow; colour of frons in full-face view often two-tone, colour lighter on lower genae (minor and media workers indistinguishable from M. sulla [sensu stricto]) (a few records from inland WA) sulla
Colour not pale, depigmented yellow 91
91 Strongly bicoloured, relatively smooth species with black, brown or variegated brown head, orange mesosoma and black gaster, gaster and often head (in darker morphs) with distinct bluish to violet iridescence; shorter setae on frons and pronotum may be expanded, mainly at their tip (arid inland Australia) (JDM 1245) (Fig. 77a–g) caeruleoviolaceus
Species without characteristic bluish or violet iridescence on gaster; erect setae on head and pronotum usually fine, erect setae often lacking entirely on mesosoma 92
92 Anterior sector of the clypeus of minor worker strongly folded back towards the mandible, and clypeal psammophore placed on a distinct ledge that may be carinate, minor worker mandible with 5-9 teeth and denticles; head, mesosoma and gaster of all workers with short, inconspicuous appressed setae that are usually separated by more than their own length on the gaster (if more elongate, as in some small minor workers, then ant is glossy and weakly sculptured); media and major workers larger (HW of large major worker ≥ 2.60 mm) wheeleri cluster (see couplet 93 below)
If clypeus distinctly folded back towards the mandible and clypeal psammophore placed on a ledge in minor worker, then head, mesosoma and gaster with relatively long, whitish, appressed setae that overlap and form a weak pubescence on the gaster and ant has distinct microreticulate or shagreenate sculpture and is matt or has a weak sheen (in such cases, minor worker with five mandibular teeth and HW of known major worker smaller than above [HW ≈ 1.45 mm]) 94
93 Head of minor worker smooth, with vestigial sculpture and often glossy; erect non-marginal setae always present on first gastral tergite, with one or two small erect setae also present on the pronotum of some individuals; eye of minor worker large (0.30× length of side of head capsule); major worker usually with many fine, erect setae on mesosoma (though these may be more sparse and bristly in a few individuals) and dark crimson or reddish-black with a glossy head capsule that is slightly lighter in colour (inland QLD, NSW, one NT record) (Fig. 80a–g) diversus
Head of minor worker always with some sculpture and matt to moderately shining in appearance; erect setae almost always lacking on pronotum and first gastral tergite, but if present (a few SA populations) then ant of intermediate appearance; eye of minor worker usually less than 0.30× length of side of head capsule; major worker similar to above, but either with glabrous mesosoma or with short, bristly setae on that part, commonly matt in appearance (WA, NT) but may be glossy (eastern states) with bright orange (rarely, dark crimson) head capsule (other Australia) (Fig. 87a–j) wheeleri
94 Clypeus distinctly folded back towards mandible and clypeal psammophore placed on a ledge in minor worker (carina may be present or absent in a given individual–if absent, check for long, appressed setae); head, mesosoma and gaster with relatively long, whitish, appressed setae that overlap and form a weak pubescence on the gaster in minor and known major workers; cuticle conspicuously shagreenate or microreticulate and matt or with a weak sheen 95
Clypeus variable in appearance (flattened or weakly protuberant or depressed anteriorly) but not distinctly folded back as above; head, mesosoma and gaster with short, inconspicuous appressed setae that are usually separated by more than their own length on the gaster (if more elongate, as in some small minor workers, then ant is glossy and weakly sculptured) 96
95 Ant uniformly brown; minor worker smaller (HW ≈ 0.70 mm) (NT, northern WA) (JDM 951) (Fig. 83a–g) parvimolaris
Ant bicoloured, with tawny orange head, antennae and mesosoma, and black gaster and legs (legs have a bluish iridescent sheen); minor worker larger (HW ≈ 0.90 mm) (major worker unknown) (inland SA, WA; a few records only) (JDM 1033) (Fig. 88a–d) xouthos
96 All workers with narrowly convex mesonotum; pronotum steeply (i.e., 60° >) inclined and flattened dorsally; minor workers with maximum of five mandibular teeth; major worker with all teeth in the same plane; bright red or reddish-orange ants with dark brown gaster (SE Australia) (Fig. 78a–g) cerasinoniger
Minor and media workers, at least, with straight or only weakly sinuous mesonotum; pronotum in minor and media workers moderately (i.e., ≈ 45°) inclined and curved throughout its length; minor workers may have more than five mandibular teeth; if major worker similar in colour and profile, then basal tooth is weakly to strongly offset 97
97 Minor worker (major worker unknown) very similar to M. fieldi complex minor workers in appearance, but with six mandibular teeth and short maxillary palps (as described in couplet 33); basal tooth the same size as the other non-apical teeth and not offset, masticatory margin of mandible almost vertical; in full-face view, anterior clypeal margin evenly convex; in profile, clypeus protuberant (as in many fieldi complex minor workers); clypeal psammophore set at midpoint of clypeal sclerite (NSW) (Fig. 81a–d) hexidens
If minor worker with combination of six teeth and clypeal psammophore set at midpoint of clypeal sclerite, then masticatory margin of mandible oblique and basal tooth distinctly offset and may be enlarged; anterior clypeal margin generally planar or nearly so in full-face view 98
98 In full-face view, broad head capsule of minor worker expanded towards mandibular insertions giving it a slight to strongly accentuated trapezoidal shape; basal margin of known major worker mandible a carinate ledge set at 90° to the rest of the mandible throughout its length, the (slightly) offset basal tooth horizontal and the sub-basal tooth with a horizontal and a vertical plane; mandibular carina present to varying degrees in media and minor workers; workers with glabrous mesosoma 99
In full-face view, sides of head capsule of minor worker convex, straight or even slightly concave, head square; apical margin of major worker mandible not completely carinate throughout its length; carina absent or reduced to a blunt edge in mandible of minor worker; erect setae present on mesosoma of nearly all M. purpureus workers (a few minor workers glabrous) and some M. chauliodon major workers 100
99 In full-face view, genae of minor and media worker strongly divergent towards anterior angles of head capsule, the latter noticeably trapezoidal, an imaginary perpendicular line drawn from the base of the eye excluding a section of the anterior clypeal margin whose width is greater than the width of the eye seen from in front; masticatory margin of mandible strongly oblique; head brown above lighter below, upper frons distinctly darker than mesosoma (large major worker not seen) (inland WA, possibly SA) (JDM 1079) (Fig. 84a–g) pelorocephalus
In full-face view, genae of minor worker weakly divergent towards anterior angles of head capsule, the latter basically square, an imaginary line drawn from the base of the eye excluding a section of the anterior clypeal margin whose width is about that of the eye seen from in front; masticatory margin of mandible weakly oblique; head and mesosoma of the same shade (i.e., tan to orange-tan) (arid inland Australia) (JDM 971) (Fig. 82a–g) laticeps
100 Eye of minor worker an elongated ellipse, length of eye ≥ 0.3 × length of side of head capsule; at least minor and media workers glabrous; major and media workers with basal mandibular tooth strongly offset to varying degrees, often tusk-like (widespread) (JDM 783) (Fig. 79a–g) chauliodon
Eye of minor worker spheroidal, length of eye ≤ 0.25 × length of side of head capsule; minor and media workers often with two or more bristly erect setae, especially on pronotum; offset basal tooth of major and media workers not prominent and never tusk-like (southwest WA) (JDM 1077) (Fig. 86a–g) purpureus
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Descriptions. (Unless otherwise stated, specimens mentioned under ‘other material examined’ are housed in the Australian National Insect Collection [ANIC]. Curtin Ant Collection material [designated ‘JDM’] is now the property of the Western Australian Museum [WAM]).

Melophorus aeneovirens species-group

This includes what are probably the most morphologically generalised Melophorus, with ancient traits. The M. aeneovirens species-group is comprised of three complexes (aenovirens, bagoti, and nemophilus). Most members of the group are elongate and gracile and include the predominant Melophorus species in cooler, wetter and more heavily forested environments, especially on the east coast, as well as parts of the Torresian zone. While some taxa have broad geographic ranges, others are known from a few collections only and appear to be highly localised. With the exception of a cluster of species around M. curtus (i.e., M. praesens, M. rufoniger and M. tenuis) the species are readily recognisable and do not pose great taxonomic difficulties.

Phylogenetically, the genetics of the M. aeneovirens species-group are highly congruent with the morphology. Despite only successfully sequencing several species, we obtained a representative species for each of the species complexes and here show that each complex is monophyletic. The M. aeneovirens complex is the most basal complex (well supported by the three- and five-gene trees), and the M. nemophilus and M. bagoti clades are sister complexes, which is reflected in the similarity in their morphological features.

Melophorus aeneovirens complex

Among all the M. aeneovirens complexes, this is the most speciose. The members of the complex are grouped together, based on several morphological features (particularly, the appearance of the anterior margin of the clypeus, the mandible, placement of the ammochaetae and the sloping appearance of the propodeum). The three-gene tree (Suppl. material 1) is the most telling when it comes to explaining the phylogeny of this complex. Based on the information derived from the successfully sequenced species, M. canus and M. griseus are sister species and the most highly derived. Interestingly, M. praesens is sister to M. platyceps in this gene tree, despite significant morphological differences (flattened body, short labial palps, etc.) that appear to place M. platyceps in its own complex.

Melophorus aeneovirens (Lowne)

Formica aeneovirens Lowne 1865: 276 (combination in Cataglyphis by Mayr 1876: 78; in Melophorus by Forel 1902: 488). Types. Syntype major and minor workers [BMNH] without collection data. (The original description by Lowne indicates an unspecified number of major and minor workers were collected near Port Jackson, New South Wales by the author in September-November, 1862.) (examined: photographs of BMNH specimens). Photograph. Melophorus constansSantschi 1928: 475. Type. Syntype major worker, Wattle Glen (as ‘Idattle’ Glen), Victoria [NHMB] (examined: AntWeb image of NHMB specimen CASENT0912336). Syn. n.

Melophorus insularis Wheeler 1934: 151. Types. Syntype media and minor workers: Rottnest Island, Western Australia [WAM, BMNH] (examined: WAM specimens Reg. Nos. E-88963/88964, AntWeb images of BMNH specimen BMNH(E)1016286, CASENT0903263). Syn. n.

Melophorus iridescens (Emery) Emery 1887: 247. Type. Syntype major worker: Mt Victoria, New South Wales [MSNG] (examined: AntWeb images of MSNG specimen [CASENT0905125]). Syn. n.

Melophorus iridescens var. froggatti Forel 1902: 487. Types. Syntype major and minor workers: Sydney, New South Wales [ANIC, MHNG] (Examined: ANIC specimens Database No. ANIC32-053436, AntWeb images of MHNGmajor and minor worker specimens CASENT0909815. CASENT0909816). Syn. n.

Melophorus iridescens var. fraudatrix Forel 1915: 87 (footnote).

Types

Syntype media and minor workers: Healesville, Victoria [ANIC, BMNH] (Examined: ANIC specimens, AntWeb images of BMNH specimen BMNH(E)1016284, CASENT0903261). Syn. n.

Other material examined

Australian Capital Territory: Black Mountain (Barnett, N.J.), Black Mt., Site 1 (Barnett, N.J. [ANIC32-029785]), Canberra (Lowery, B.B.), Capital Hill, Canberra (Lowery, B.B.), Lees Spring (Greaves, T.), Mt. Ainslie (Greaves, T.), Mt. Ainslie (Lowery, B.B.), Mt. Stromlo (Greaves, T.). New South Wales: 14 km SW Cootamundra (Lowery, B.B.), 2 mi S Mt Cambewarra (Lowery, B.B.), 8 km S Shooters Hill, 28 km S Oberon (Shattuck, S.O.), Barellan (Lowery, B.B.), Canobolas State Forest (Gush, T.), Condobolin (Lowery, B.B.), Cowan, Sydney (Lowery, B.B.), Fowlers Gap Research Station (Naumann, I.D. & Cardale, J.C.), Lane Cove, Burns Bay, Sydney (Lowery, B.B.), Maroota State Forest (Gush, T.), Memorial Drive, Armidale (Lowery, B.B.), Mudgee (Lowery, B.B.), Myall Lakes National Park (York, A.), near Deniliquin (Zakharov), near Deniliquin (Zakharov [ANIC32-013875]), Newholme Road, near Armidale (Sakurai, Y.), Putty, 50 mi N Windsor (Lowery, B.B.), Pymble (Lowery, B.B.), Royal National Park (Gush, T.), Spring Range Park, 7.5 km NE Hall (Shattuck, S.O. [ANIC32-053450]), The Gib, Bowral (Lowery, B.B.), The Rock Nature Reserve, about 20 mi SE Wagga Wagga (Lowery, B.B.), Tomago (Jackson, G.P. [ANIC32-015239]), West of foothills, Tinderry Mountains (Lowery, B.B.), Whiporie, 55 km S Casino (York, A.). Queensland: 2 km N Charleville (Edwards, E.D. & Fisk, J.H.), Gregory Dev. Rd, Sardine Ck (Monteath & Cook), N. Stradbroke Is. Enterprise (QM Party), Toowoomba (Greaves, T.). South Australia: 10 km SW Meningie (Greenslade, P.J.M.), 13 km S Quorn, Flinders Ranges (Greenslade, P.J.M.), 15 km ENE Beltana (Greenslade, P.J.M.), 19 mi NW Port Lincoln (Greaves, T.), 22 mi E Eucla (Greaves, T.), 2 km S Ravine des Casoars, Kangaroo Island (Greenslade, P.J.M.), 30 km E Poeppel Corner, Simpson Desert (Greenslade, P.J.M.), 48 km E Minnipa (DEH Surv. 587-KDO 014 [M83]), 4 km S Salt Creek, Coorong (Greenslade, P.J.M.), 7 km W Penneshaw, Kangaroo Island (Greenslade, P.J.M.), Adelaide (Lea), Alligator Creek, South Flinders Range (Greenslade, P.J.M.), Banff, Coorong (Greenslade, P.J.M.), Belair (Greenslade, P.J.M.), Belair (Greenslade, P.J.M.), Bridgewater (Greenslade, P.J.M.), Bridgewater (Baker, G.F.), Calca (Lowery, B.B.), Cambrai (Greenslade, P.J.M.), Ceduna (Lowery, B.B.), Ceduna (Casperson, K.), Cleland, Mt. Lofty Ranges (Yeatman, E.), Cockatoo, Coorong (Greenslade, P.J.M.), Cockatoo, Coorong (Greenslade, P.J.M.), Glen Osmond (Greenslade, P.J.M.), Koonamore (Greenslade, P.J.M.), Kuitpo (Greenslade, P.J.M.), Mambray Creek (Greenslade, P.J.M.), Messert Res., Coorong (Greenslade, P.J.M.), Napperby, Flinders Ranges (Greenslade, P.J.M.), North of Breakneck River, Kangaroo Island (Greenslade, P.J.M.), North of Breakneck River, Kangaroo Island (Greenslade, P.J.M.), Oraparinna, Flinders Ranges (Greenslade, P.J.M.), Para Wirra (Greenslade, P.J.M.), Scrubby Gully, Sevenhill (Lowery, B.B.), Sevenhill (Lowery, B.B.), Sevenhill (Lowery, B.B.), Sevenhill (Lowery, B.B.), Sevenhill (Lowery, B.B.), Sevenhill (Lowery, B.B.), Victor Harbour (Greenslade, P.J.M.), West Bay, Kangaroo Island (Greenslade, P.J.M.). Victoria: Anglesea (Andersen, A.N. [JDM32-001829]), 15 km WNW Yaapeet (Andersen, A.N.), Bendigo (McAreavey, J.), Big Desert (Andersen, A.N.), Bull Creek, Glenaladale National Park (Andersen, A.N.), Heathcote, near Bendigo, Mt. Ida (Lowery, B.B.), Kew (McAreavey, J.), Wangarratta (Bruce, W.A.), Watsonia (Lowery, B.B.), Wattle Park, Melbourne, Werribee (Lowery, B.B.). Western Australia: 14 km S of Billabong R/D House, Nth/West Coastal Hwy (Heterick, B.E. [JDM32-001495]), 24 mi ESE Broome (McInnes & Dowse [ANIC32-900075]), 49 mi WSW Ravensthorpe (Greaves, T.), 4 km NW of Gleneagle (Heterick, B.E. & Jacobs, M. [JDM32-001494]), 8 mi E Northcliffe (Taylor, R.W.), Albany (Greaves, T.), Alcoa (Wallace, J.), Bartons Mill (Majer, J.D.), Bartons Mill (Majer, J.D. [JDM32-001521]), Black Swan Mine (Langlands, P. & Osbourne, J. [JDM32-001496]), Bunbury (Lowery, B.B.), Canning Vale (Knowles, D.G. [JDM32-001498]), Coalmine Beach, Nornalup National Park, Walpole (Lawrence, J. &N.), Coalmine Rd. (collector unknown [JDM32-001830]), Denmark (Lowery, B.B.), Dwellingup (Majer, J.D.), Dwellingup (Majer, J.D. [JDM32-001500]), Eneabba (Fox, J. [JDM32-001533]), Goora Hill [Gora Hill]] (Greaves, T. [ANIC32-052115]), Gora Hill (Greaves, T.), Harvey (Mercovich, C.), Jandakot (collector unknown [JDM32-001530]), Jandakot (collector unknown [JDM32-001529]), Jurien (collector unknown [JDM32-001532]), Kalamunda (Greaves, T.), Kalbarri National Park (Ward, P.S.), Kings Park, Perth (Lowery, B.B.), Kojonup (Majer, J.D. [JDM32-001512]), Manjimup (Majer, J.D. [JDM32-001509]), Melaleuca Grove, Thomas River (Greaves, T.), Mordalup (Majer, J.D. [JDM32-001531]), Mt. Clare, 4 mi W Walpole (Taylor, R.W.), Mt. Ragged, west foot (Taylor, R.W.), Mulga, NE Goldfields (Pringle, H.J.R. [ANIC32-029627]), Mundaring (Clark, J.), nr. Wungong Dam (Heterick, B.E. [JDM32-001493]), Perth (Clark, J.), Reabold Hill (Majer, J.D. [JDM32-001534]), Red Hill (Heterick, B.E. [JDM32-001492]), Rottnest Is. (collector unknown [JDM32-001536]), Rottnest Island (Lea), Talyuberlup Picnic Area, Stirling Range National Park (Lawrence, J. &N.), Telegraph Hill, Esperance (Lowery, B.B.), Without Locality (Majer, J.D. [JDM32-001535]).

Diagnosis

Melophorus aeneovirens is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. aeneovirens the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the minor worker mesosoma is compact and is arcuate in outline. Melophorus aeneovirens can be distinguished from similar species by having, in profile, the clypeus distinctly recurved at about midpoint and produced over the mandible as a small ledge; in full-face view, the anterior margin of the major and minor worker clypeus forms a broadly convex, sometimes crenulate curve that does not protrude over apical the curve of mandible.

Minor worker description

Head. Head square; posterior margin of head strongly convex; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal margin entire or very weakly indented, or narrowly convex and protruding anteromedially, clypeal midpoint distinctly notched; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove deep, ‘V’-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node generally rounded with median indentation or hollow; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of long, closely aligned, whitish, appressed setae, with erect setae (present in at least some workers) confined to margin of sclerite. General characters. Colour of foreparts reddish-brown through red to dark crimson, legs dark brown, gaster blackish-brown to black.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head strongly concave; cuticle of frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal margin entire or weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae short (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts reddish-brown through red to dark crimson, legs dark brown, gaster blackish-brown to black.

Measurements

Worker (n = 6): CI 91–115; EI 14–28; EL 0.19–0.34; HL 0.73–2.12; HW 0.67–2.44; ML 1.15–2.47; MTL 0.60–1.39; PpH 0.13–0.25; PpL 0.61–1.15; SI 67–142; SL 0.95–1.62.

Comments

Melophorus aeneovirens (Lowne) was the first Melophorus species to be described, and was originally placed in the genus Formica. This is among the most common of all the Melophorus species, and is found in all mainland states. This ant is particularly common on the eastern seaboard, but does not appear to occur in Tasmania. Regrettably, despite its abundance in many areas, no specimens were available for sequencing. In general, there is some morphological variation, particularly among minor workers that could be examined using genetic markers (some of this variation is mentioned by Wheeler (1934) in his description of M. insularis). Colour varies from orange to blackish-brown among minor workers and the degree of compression of the dorsum of the propodeum also varies: in some cases this sclerite is rather convex in outline but it can be straight or even fractionally concave. The metanotal groove varies from deeply to weakly incised. Minor workers among different populations can also vary markedly in size and sculpture. However, all minor workers share the recurved appearance of the clypeus when this is seen in profile, an asymmetrical vertex (like M. praesens and M. rufoniger) and an anterior clypeal margin that is never strongly produced so as to form a ledge (this feature serves to separate M. aeneovirens from nearly all other members of the M. aeneovirens species-group). Because of its ubiquity, M. aeneovirens has attracted a lot of taxonomic attention, and M. constans, M. insularis, iridescens, M. iridescens froggatti, and M. iridescens fraudatrix all reveal consistency as regards the diagnostic characters determined for the species in this revision and become junior synonyms in this work. Furthermore, M. aeneovirens from Port Jackson and M. iridescens froggatti from Sydney come from the same population. The major worker in each case has an orange head and dark brown body and blackish gaster.

The distribution of this taxon is predominantly southern and most collections have been taken in mesic, coastal localities, with far fewer records from arid and semi-arid areas. This is the common Melophorus species taken in well-watered forests. Lowne (1865) mentions this ant formed small nests with an inconspicuous opening, and nests in Port Jackson NSW (the type locality) were usually concealed under leaves or stones. The habits of M. aeneovirens may well be mentioned in the literature without the species being identified, but little has been recorded under that name or under the synonymic names. Since this species occurs in a very wide range of habitats, including grassy lawns of suburban residences, the most logical inference is that it is a generalized scavenger.

Figure 6. 

Melophorus aeneovirens (Lowne): BMNH major worker syntype frons (a), profile (b) and dorsum (c); BMNH minor worker syntype frons (d), profile (e) and dorsum (f); distribution map for the species (g).

Melophorus attenuipes Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant) from 1 km N Mulga Downs OC 22°19'33"S, 118°58'47"E, Western Australia, 24 May 2004-4 May 2005, CALM Pilbara Survey, Site RHNW05, ethylene glycerol pitfalls [JDM32-002000] (WAM). Paratypes: major worker, on same pin and with same details as holotype (WAM); minor worker, Zuytdorp 27°15'S, 114°04'E, Western Australia, 26 September-19 October 1994, A. Sampi/L. Cresswell, ZU4: Wet pits WAM/CALM survey Carnarvon Basin [JDM32-001998] (ANIC); minor worker, Zuytdorp 27°15'S, 114°04'E, Western Australia, 26 September-19 October 1994, A. Sampi/L. Cresswell, ZU4: Dry pits WAM/CALM survey Carnarvon Basin [JDM32-001999] (MCZ).

Diagnosis

Melophorus attenuipes is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). The Minor worker of this species is characterised as being very small (HW ≤ 0.50 mm), but it is the metafemur of the minor worker that is the best diagnostic charcter. This body part is attenuated to the midpoint and thereafter is of uniform width until its junction with the tibia (the media worker has a similar metafemur, but the attenuation is more gradual and less conspicuous). The head of the minor worker rather elongate and very strongly domed. The major worker can best be identified by the flattened anteromedial sector of its clypeus, this sector not extending beyond the lateral flanks of the clypeus.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set at about midpoint of head capsule; in profile, eye set around midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae distinctly concave; frontal lobes curved toward antennal insertion. Anteromedial clypeal margin broadly and evenly convex; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen and superficial microreticulation (more pronounced on mesopleuron); anterior mesosoma in profile smoothly rounded anteriad, thereafter pronotum and whole of mesonotum flattened and on same plane as propodeum; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae always absent; appressed propodeal setulae sparse or absent, if present then not regularly spaced; propodeal spiracle situated on or beside declivitous face of propodeum, and longer (length ≥ 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of head and foreparts tan, gaster chocolate, coxae and femora brown, tibia and tarsi mainly depigmented yellowish.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head weakly convex; cuticle of frons matt or with weak sheen, microreticulate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, convergent posteriad; frontal lobes curved inward in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal margin entire or weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile smoothly rounded anteriad, thereafter pronotum and whole of mesonotum flattened and on same plane as propodeum; erect pronotal setae absent; in profile, metanotal groove deep, V-shaped; propodeum matt or with a weak sheen and microreticulate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and longer (length ≥ 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node tapered with squared-off vertex; node matt, shagreenate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae, erect setae (present in at least some workers) confined to margin of sclerite. General characters. Colour of foreparts and legs orange tan (head slightly more reddish), gaster chocolate.

Measurements

Worker (n = 3): CI 80–114; EI 20–32; EL 0.15–0.31; HL 0.56–1.37; HW 0.45–1.57; ML 0.74–1.69; MTL 0.53–1.10; PpH 0.09–0.18; PpL 0.42–0.72; SI 79–156; SL 0.70–1.24.

Comments

The minor worker of this small species is recognizable by virtue of its small size (HW ≤ 0.50mm), much attenuated and long hind femur and strongly domed vertex. The media and major workers are less easily characterized, but the major worker has a flattened clypeus. The species appears to be restricted to the mid-west and Pilbara regions of Western Australia, and is known from a couple of collections only (WAM, one TERC record). Nothing is known of its biology or its genetics.

Etymology

Compound of Latin ad (‘towards’) plus tenuis (‘thin’) and Greek pes (pl. of pous ‘foot’); adjective in nominative singular.

Figure 7. 

Melophorus attenuipes sp. n.: major worker paratype (JDM32-002000–top ant) frons (a), profile (b) and dorsum (c); minor worker holotype (JDM32-002000–bottom ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus canus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from Goora Rock area, 70 miles from Esperance, Western Australia, 23 December 1969, B.B. Lowery, limestone mallee under rock [ANIC32-900003] (ANIC). Paratypes: 2 media workers, major worker and minor worker on same pin and with same details as the holotype (ANIC); 3 minor workers and major worker from Denmark, Western Australia, 19 December 1969, B.B. Lowery [ANIC32-900001] (BMNH); 2 minor workers, media worker, 3 major workers and male from Trundle, New South Wales, 9 January 1964, B.B. Lowery, in red soil, box pine scrub, Y35 [ANIC32-900005] (MCZ); minor worker from 107.2 km SSE of Newman 23°53'54"S, 120°36'14"E, Western Australia, October 1996, S. van Leeuwen & R. N. Bromilow, Invert., pitfall trap S3, Sand plain [JDM32-001987] (WAM).

Other material examined

Queensland: ‘Merigol’ (Beutel, T.), Billabong W Salty Bore, Cravens Peak Station (Lemann, C. [ANIC32-035406]). South Australia: Black Oak Creek, Koonamore (Greenslade, P.J.M. [ANIC32-900004]). Western Australia: 0.9 km along Tanami Rd (Heterick, B.E. [M202]), Geraldton (Clark, J. [ANIC32-900002]), Mumbemarra Hill (10 km E of Geraldton) (Heterick, B.E. [JDM32-001986]).

Diagnosis

Melophorus canus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). This particular species is distinctive because the main teeth of the mandible are supplemented with small or indistinct denticles, the total number of teeth and denticles ≥ six. Also, in full-face view, the head of the minor worker is indented below the eye, giving a bell-shaped appearance to the head capsule. This latter character is shared only with M. griseus, which, however has the typical unmodified Melophorus mandible. The species has a very dull, shaggy appearance, the workers being matt, shagreenate, and with very many long, flexuous setae over silvery pubescence.

Minor worker description

Head. Head approximately oval, sides of head divergent towards mandibular articulations; posterior margin of head strongly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; pilosity of frons a mixture of many long, curved, semi-erect setae and decumbent and appressed setae of varying lengths that form a coarse pubescence. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex, or straight, divergent posteriad; frontal lobes straight in front of antennal insertion, or curved inward in front of antennal insertion. Anteromedial clypeal margin narrowly protrusive anteromedially, the protrusion with a square border; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Mandibular teeth in minor worker consisting of four distinct apical teeth with the basal denticle separated by one to several minute denticles or crenulations; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae long (i.e., longest erect setae longer than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 3:2 and 4:3; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of a mixture of curved, erect and semi-erect setae and decumbent and appressed setae that form a variable pubescence. General characters. Colour brown or black (concolorous or bicoloured).

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head planar or weakly concave; cuticle of frons matt or with weak sheen, microreticulate; pilosity of frons a mixture of many long, curved, semi-erect setae over well-spaced short semi-erect, decumbent and appressed setae. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal margin entire or weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Mandibular teeth in major worker consisting of four distinct apical teeth with the basal denticles separated by one to several minute denticles or crenulations; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; erect pronotal setae long (i.e., longer than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 3:2 and 1:1; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length less than 0.50 × height of propodeum), or situated at least twice its width from the declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of a mixture of curved, erect and semi-erect setae and decumbent setae that form a variable pubescence. General characters. Colour dark reddish-brown.

Measurements

Worker (n = 6): CI 87–111; EI 21–43; EL 0.31–0.41; HL 0.83–1.72; HW 0.72–1.91; ML 1.29–1.93; MTL 0.77–1.00; PpH 0.16–0.22; PpL 0.51–0.80; SI 57–137; SL 0.98–1.08.

Comments

Melophorus canus is widely distributed throughout mainland Australia but is nowhere particularly common. The species is rendered distinctive by the long flexuous setae over thick, shining grey, appressed pilosity (hence the name), the somewhat bell-shaped appearance of the head of the minor worker when seen in full-face view and the appearance of the mandible. Genetic sequencing places it as the sister species to M. griseus. Collections have been made in a variety of habitats and geographic zones, and vegetation associations include limestone mallee and box-pine scrub but the habits of this species are unknown. A picture of the minor worker is found in fig. 15d in Greenslade 1979.

Etymology

Latin canus (‘grey’ or ‘hoary’); adjective in nominative singular.

Figure 8. 

Melophorus canus sp. n.: major worker paratype (ANIC32-900003–third ant from top) frons (a), profile (b) and dorsum (c); minor worker (ANIC32-900003–top ant) holotype frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus castaneus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant) from Gawler Ranges, South Australia, 5 October 1972, P.J.M. Greenslade, (8) [ANIC32-900180] (ANIC). Paratypes: major worker and media worker on same pin and with same details as holotype (ANIC); minor worker from 2 km E of Cowangie 35°14'S, 141°24'E, Victoria, 5 November 1991, S. Shattuck #2617.7 (ANIC); 3 minor workers from Kunoth Paddock, near Alice Springs, Northern Territory, 24-26 September 1980, P.J.M. Greenslade, Part A., (MCZ); minor worker from Sturt National Park, New South Wales, November 1979, P.J.M. Greenslade, Traps 2, 40) (BMNH); 2 minor workers from Kunoth Paddock, near Alice Springs, Northern Territory, 24 [September]- 8 October 1974, P.J.M. Greenslade, G. (QM); minor worker from 105 km N of Yuendumu, Northern Territory, 23 May 1986, P.J.M. Greenslade, (12), (Mu15) (SAM); media worker from Ethel Creek, Western Australia, 1993-4, P.A. Varris, ID: Melophorus froggatti Forel [sic], Det. by: Heterick, B.E., Date: 14 November 2006, checked against syntype specimen [M. froggatti is here regarded as a junior synonym of the closely related and similar M. aeneovirens-BEH] [ANIC32-004580) (WAM).

Other material examined

New South Wales: 40 km NNW Louth, Lake Mere (Greenslade, P.J.M.), Bogan River (Armstrong, J.), CSIRO Lake Mere Field Station, near Louth (Bryannah, M.). Northern Territory: Kunoth Paddock, near Alice Springs (Greenslade, P.J.M.), Melville Island (Hoffmann, B.). Queensland: 42 mi NW Julia Creek (Dowse, J.E.), 4 mi ESE Toobeah (Greaves, T.). South Australia: 2.8 km NNW Four Hills Trig. Peake Stn (Stony Desert Survey UB02 [M90]), 7 km NW Morgan (Greenslade, P.J.M.). Western Australia: Ethel Creek (Varris, P.A. [JDM32-001499]), 10 mi NNW Gordon Downs Homestead (McInnes & Dowse [ANIC32-900085]), 11 km W Terhan Water Hole (Heatwole, H.).

Diagnosis

Melophorus castaneus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. castaneus the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). The minor worker of Melophorus castaneus can readily be distinguished from its nearest relatives (M. clypeatus, M. praesens and M. rufoniger) by the uniformly rounded appearance of the vertex of the head when seen in full-face view, and by the uniformly convex propodeum. The major worker is less distinctive, but generally has the rounded propodeum seen in the minor worker, wheareas the M. praesens major worker propodeum is more sloping. The major worker clypeus also lacks the well-developed medial flange found in the major worker of M. rufoniger and is smaller (HW of the former has a HW of ≤ 2.10mm versus > 3 mm in M. rufoniger). The major worker of M. clypeatus also has a more protrusive clypeal flange than does the major worker of M. castaneus.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons shining with superficial shagreenation or microreticulation only, or matt or with weak sheen, shagreenate; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only, or consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and finely striolate and microreticulate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae long, each reaching setae behind and in front, but not forming pubescence, or short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node rectangular, its vertex blunt, directed posteriad; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts and appendages brown, gaster dark brown.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head weakly concave; cuticle of frons matt or with weak sheen, microreticulate; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; roughly ovoid, eye narrowed posteriad. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove deep, V-shaped; propodeum matt or with a weak sheen and microreticulate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae absent; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial microreticulation anteriad. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, short, thick, erect setae interspersed with minute, appressed setae. General characters. Colour of head and legs reddish-tan, mesosoma brownish-orange, gaster black.

Measurements

Worker (n = 8): CI 84-111; EI 18-26; EL 0.21-0.37; HL 0.95-1.88; HW 0.79-2.08; ML 1.41-2.25; MTL 0.83-1.41; PpH 0.13-0.27; PpL 0.63-0.93; SI 77-147; SL 1.16-1.60

Comments

This very typical member of the M. aeneovirens species-group is distinguished from similar species by the combination of its rounded propodeum (rather angulate in the similar M. praesens), the shape of its clypeus (less projecting than in M. rufoniger) and the lack of asymmetry in the vertex of the head capsule in the minor worker. The tibiae have socketed setae only, enabling it to be distinguished from morphologically similar populations of M. curtus. This species is most common in drier habitats, where it is likely to be a generalized forager, and it has a wide distribution in mainland Australia. However, this ant seems to be more common in eastern and central parts of the country. Some workers have been collected in modified habitats such as paddocks and rehabilitated grasslands. No specimens were available for sequencing during this project, but the appearance strongly suggests that the genetics of M. castaneus will eventually prove to be similar to those of M. rufoniger and M. praesens.

Etymology

Latin castaneus (‘chestnut’ [i.e., coloured]); adjective in nominative singular.

Figure 9. 

Melophorus castaneus sp. n.: major worker paratype (ANIC32-900180–top ant) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900180–bottom ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus clypeatus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant) from 19.8 km WNW of Mt Berry 22°25'47"S, 116°16'47"E, Western Australia, 9 September 2003-10 October 2004, CALM Pilbara Survey, Site WYE10, Ethylene glycol pitfalls [JDM32-001497] (WAM). Paratypes: major and minor worker on same pin and with same details as the holotype (WAM); major and 2 minor workers on separate pin with exactly same details as the above (ANIC).

Diagnosis

Melophorus clypeatus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. clypeatus the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the minor worker mesosoma In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly. Melophorus clypeatus can be distinguished from from the (likely closely related) M. praesens by the narrow, rectangular, flanged appearance of the anteromedial margin of the clypeus in both major and minor workers, the flange having a straight or weakly indented edge.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes curved toward antennal insertion. Anteromedial clypeal margin narrowly protrusive anteromedially, the protrusion with a square border; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove a weak or vestigial furrow; propodeum shining and shagreenate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae sparse or absent, if present then not regularly spaced; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node square with rounded angles; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour tan, gaster chocolate.

Major worker description

Head. Head square; posterior margin of head weakly concave; cuticle of frons matt or with weak sheen, microreticulate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and finely striolate and microreticulate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae absent; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node tapered with blunt vertex, or tapered with squared-off vertex; node matt, shagreenate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, short, thick, erect setae interspersed with minute, appressed setae. General characters. Colour tan, gaster chocolate.

Measurements

Worker (n = 2): CI 93–108; EI 16–25; EL 0.23–0.37; HL 0.96–2.09; HW 0.89–2.26; ML 1.52–2.27; MTL 0.89–1.31; PpH 0.13–0.20; PpL 0.71–1.10; SI 73–149; SL 1.33–1.65.

Comments

Our knowledge of Melophorus clypeatus is restricted to two collections (ten workers) taken from the Pilbara region of Western Australia (WAM) and several records from TERC (one from Mt Isa, QLD). Nothing is known of its habits or biology, but the close resemblance to M. praesens (from which it differs only in colour and in the appearance of the clypeus) suggests similar habits to the latter.

Etymology

Latin clypeus (‘armed with a shield’ [referring to the prominent clypeus]); noun in the nominative singular standing in apposition to the generic name

Figure 10. 

Melophorus clypeatus sp. n.: major worker paratype (JDM-001497–top ant) frons (a), profile (b) and dorsum (c); minor worker holotype (JDM32-001497–bottom ant on separate pin) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus curtus Forel

Melophorus curtus Forel 1902: 485.

Types

Syntype small major worker, MacKey, Queensland [ANIC], here designated lectotype: (examined: ANIC specimen ANIC32-053434). Also examined: syntype minor worker with same details as lectotype [ANIC], here designated a paralectotype; AntWeb images of syntype major and minor worker, MacKey, Queensland [BMNH] (CASENT0903264, CASENT0903265), here designated paralectotypes; AntWeb images of syntype major and minor worker, MacKey, Queensland [MHNG] (CASENT0909810, CASENT0909811), here designated paralectotypes. Also designated a paralectotype is a syntype queen [MHNG] (Taylor and Brown 1985), not seen.

Other material examined

New South Wales: 40 km W Hillston (Greenslade, P.J.M. [ANIC32-900023]), Armidale (Lowery, B.B. [ANIC32-900016]), Armidale, west of golf course (Lowery, B.B. [ANIC32-900015]), Bogan River (Armstrong, J. [ANIC32-900017]), Bourke (Barrett, C.L. [ANIC32-900018]), Emmett Vale (Valentine [ANIC32-900020]), Hay (Lowery, B.B. [ANIC32-900021]), Hillston, The Common (Lowery, B.B. [ANIC32-900022]), Lachlan River, Condobolin (Lowery, B.B. [ANIC32-900019]), Mungindi (Lowery, B.B. [ANIC32-900024]), Round Mountain (NE NSW) (Lowery, B.B. [ANIC32-900025]), Whiporie, 55 km S Casino (York, A. [ANIC32-900026]). Northern Territory: CSIRO TERC, Darwin (Shattuck, S.O. [ANIC32-047317]), Hills, 27 km SW Katherine (Greenslade, P.J.M. [ANIC32-900009]), Kapalga, Alligator Rivers area (Greenslade, P.J.M. [ANIC32-900007]), Kapalga, Kakadu National Park (Andersen, A.N. [ANIC32-900008]), Manbullo I., SW Katherine (Greenslade, P.J.M. [ANIC32-900010]). Queensland: ‘Merigol’ (Beutel, T.), ‘Paingo’ turnoff (Monteath & Cook), ‘Wallaroo’ Hwy; 6 km WNW (Burwell/Monteath), 33 mi SSW Tara (Dowse, J.E. [ANIC32-900014]), Blackwood NP (Monteath & Cook), Blair Athol Mine (Houston, W. [ANIC32-040330]), Corry HS, 2 km SW, Retro-Corry Rd (Burwell), Fanning R Hmstd, 3.3 km SE (Monteith & Cook), Illaweena St. Drewvale (QM Party), Koondooloo, Hannaford Rd North via Tara (House, A./Brown, S.), Lizard Island (Reichel, H. [ANIC32-900011]), Lolworth NP (Wright, S.), Lords Table (Burwell), Moolayember Ck NP (Wright/Burwell), Moolayember Ck NP (Wright/Burwell), Moolayember Ck NP (Wright/Burwell), Mt Castor, 0.5 km W (Burwell/Monteath), Mt Pollux, SW base (Burwell, C.), Mt Pollux, SW base (Burwell, C.), N. Stradbroke Is. Enterprise (QM Party), Proserpine, Thompson Creek (Raven & Burwell), Ransome Reserve (QM Party), Redlands Hilliards Ck, nr South St (RHC1) (Stanisic, J.), Redlands Hilliards Ck, nr South St (RHC1) (BAAM/QM Party), St George (Lowery, B.B. [ANIC32-900013]), St George (Lowery, B.B. [ANIC32-900012]), Springsure, 16 km N (Monteath, G.), Tindaree, Hannaford Rd South via Tara (House, A./Brown, S.), Tindaree, Hannaford Rd South via Tara (House, A./Brown, S.), Wolfgang Peak (Burwell, C.J./ Monteath, G.). Victoria: Patho (Potter, H.A. [ANIC32-900027]), Patho (Potter, H.A. [ANIC32-039539]). Western Australia: Argyle Diamond Mine via Kununurra (Postle, A. [JDM32-004540]), Mulga, NE Goldfields (Pringle, H.J.R. [ANIC32-029573]), Packsaddle (van Leeuwen, S. [JDM32-004542]), Pilbara locality unknown (Unknown [JDM32-004539]), Tropicana minesite (Summerhayes, J. [JDM32-004541]).

Diagnosis

Melophorus curtus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. curtus the tibiae possess fine, appressed pubescence in addition to stout, socketed, appressed to subdecumbent setae This species differs from M. sulconotus in the appearance of the mesosoma, which, in profile, has a pronotum and mesonotum that are weakly to strongly convex in the minor worker, The antennal scapes and tibiae lack bristly erect and semi-erect setae, and short, erect setae are normally sparse on dorsum of mesosoma. The head of the minor worker is oval or squared and the frontal triangle is triangular in appearance. This combination of characters separates M. curtus from M. gibbosus and M. griseus, which share the pilosity pattern seen on the metatibae in M. curtus. Both M. griseus and M. gibbosus have erect setae on the antennal scape and the tibiae. The major worker of M. curtus can also be distinguished from that of M. gibbosus (the major worker of M. griseus is unknown) by its partially shagreenate frons, the frons being microreticulate in the M. gibbosus major worker.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons matt or with weak sheen, shagreenate; frons consisting almost completely of appressed setae that may form pubescence (tiny, erect setae, if present, usually confined to ocular triangle). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal margin entire or very weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified, or erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae variable in number, may be absent; appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node square with rounded angles; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae, or consisting of long, closely aligned, whitish, appressed setae, with erect setae (present in at least some workers) confined to margin of the sclerite. General characters. Colour brown, gaster slightly darker in some workers.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head weakly concave; cuticle of frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. Eye small (eye length less than 0.2 × length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae concave; frontal lobes curved inward in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and sparse to moderate (1-12); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded, or generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour of foreparts orange-red, gaster brown to black.

Measurements

Worker (n = 8): CI 87–109; EI 15–31; EL 0.18–0.40; HL 0.68–2.40; HW 0.59–2.62; ML 0.94–2.81; MTL 0.57–1.81; PpH 0.11–0.35; PpL 0.49–1.23; SI 72–149; SL 0.88–1.90.

Comments

Most collections of Melophorus curtus have been made in Eastern Australia, where it is quite common, but no specimens were available for sequencing. There is some doubt that the taxon, as defined here, is monophyletic: although it is characterized by the presence of fine, appressed pubescence of the tibiae in addition to stout, socketed, appressed to subdecumbent setae, and also the absence of erect setae on the antenna and hind tibiae, other features are very variable, especially in the minor worker. Quite compressed, short-legged, relatively hairy workers are common in the Armidale area of NSW, while larger, more elongate and glabrous or near glabrous workers are common further north. In northern Australia a very elongate form with long, silvery, appressed setae on the head and body occurs. (However, this ant may represent the media worker of M. tenuis, which is here described on the basis of the minor only.) The moderately gracile morphotype, which is the most common, can also easily be mistaken for M. praesens or M. castaneus, and the tibiae of specimens must be examined carefully to distinguish the former species from the latter two. The possibility that there could be at least two or three cryptic species cannot be discounted, and further investigation involving genetics work is desirable in order to unravel the phylogenetics of such variable populations. A small syntype major worker from MacKey is here designated lectotype. This specimen not only represents the most common morph of M. curtus but has clearly recognizable defining features that belong to this taxon. The other syntypes here become paralectotypes.

Based on label data, this ant has a predilection for black soil, and has been taken in both dry sclerophyll woodland and savannah. Pitfall traps are a common means of capture. In all likelihood this species is a generalized scavenger.

Figure 11. 

Melophorus curtus Forel: non–type major worker (ANCI32-900019–top ant) frons (a), profile (b) and dorsum (c); non–type minor worker frons (ANCI32-900019–bottom ant) (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (a–c); 0.5 mm (d–f).

Melophorus fulgidus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant) from Coward Springs 29.24S, 136.49E, South Australia, 22 September 1972, J. E. Feehan, ANIC Ant Vial 16.70 [ANIC32-066609] (ANIC). Paratypes: major and minor worker on same pin with same details as holotype (ANIC); queen and 2 minor workers from Coward Springs 29.24S, 136.49E, South Australia, 22 September 1972, J. E. Feehan, ANIC Ant Vial 16.70 [ANIC32 900006] (MCZ).

Diagnosis

Melophorus fulgidus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). Melophorus fulgidus is not particularly distinctive, but can be identified in having, in full-face view, the eyes of the minor worker placed high on the head and breaking the outline of head capsule where the broadly convex posterior margin of the head meets the sides. Unlike most membes of the species-complex, both major and minor worker are glabrous, smooth and shining, with the appressed setae spaced much greater than their own length apart. In profile, the major worker has a flat mesonotum that overarches the pronotum, and, in full-face view, a protruding, weakly bifurcate anteromedial clypeal margin. This combination of characters separate M. fulgidus from other Melophorus in its species-complex, but careful checking is required. The species appears to be very localised in the Flinders Ranges in mid-north South Australia.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, convergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly protrusive anteromedially, the protrusion with a square border; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and uniformly striolate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour brown.

Major worker description

Head . Head square; posterior margin of head weakly concave; cuticle of frons matt or with weak sheen, indistinctly shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, convergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and shagreenate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae absent; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of head orange, remainder of body brown.

Measurements

Worker (n = 2): CI 94–109; EI 19–29; EL 0.26–0.36; HL 0.94–1.75; HW 0.88–1.90; ML 1.54–2.18; MTL 1/03–1.37; PpH 0.15–0.20; PpL 0.69–0.90; SI 85–152; SL 1.34–1.61.

Comments

This species is known from two pins, both from Coward Springs, South Australia. The highly polished appearance, the overlapping mesonotum in the major worker and the high placement of the eyes on the head capsule in the minor worker help to distinguish this species from similar species in the M. aeneovirens group. Nothing is known of its biology.

Etymology

Latin fulgidus (‘gleaming’); participle in nominative singular.

Figure 12. 

Melophorus fulgidus sp. n.: major worker (ANIC32-066609–top ant) paratype frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-066609–bottom ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g).

Melophorus gibbosus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker from Alligator Creek, S. Flinders Ra., South Australia, 23 April 1973, P.J.M. Greenslade [ANIC32-900191] (ANIC). Paratypes: 2 major workers, 2 minor workers, 1 alate queen, 1 male from Watsonia, Victoria, 24 May 1958, B. B. Lowery, ‘Melophorus biroi’ [sic] [ANIC32-900073] (BMNH); 3 minor workers from CSIRO Lake Mere field stn near Louth, New South Wales, paddock B Grove, January 1995, M. Bryannah, ‘Meloph. sp. × 6’ (MCZ); minor worker from Bauple, Queensland, August 1996, C. Vanderwoude, S.F. 958 E. maculata open forest plot 11 cpt 19, Melophorus sp. B (QM), 1 media worker from Fowlers Gap, New South Wales, November 1979, P.J.M. Greenslade, Traps 5 (27) (WAM).

Other material examined

Queensland: ‘Merigol’ (Beutel, T.), Proserpine, Deadman Creek (Raven, R.), Tindaree, Hannaford Rd South via Tara (House, A./Brown, S.). South Australia: Mt. Remarkable, Flinders Ranges (Greenslade, P.J.M. [ANIC32-900072]), Oraparinna, Flinders Ranges (Greenslade, P.J.M.). Western Australia: Queen Victoria Spring (CALM [JDM32-001570]), Westonia (Harris, R. et. al. [JDM32-001569]).

Diagnosis

Melophorus gibbosus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. gibbosus the tibiae possess fine, appressed pubescence in addition to stout, socketed, appressed to subdecumbent setae. Unlike its near relative, M. griseus, the frontal carinae of the worker are not raised or laminate at the edges; the frontal triangle is triangular in appearance and the sides of the head of minor worker are not divergent below eyes. In profile, the pronotum and mesonotum form a strong convexity, and this is very distinctive of the ant. The major worker also has a uniformly microreticulate head.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head weakly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eye more-or-less circular. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour concolorous brown.

Major worker description

Head. Head oval; posterior margin of head planar or weakly convex; cuticle of frons matt or with weak sheen, microreticulate; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt with indistinct shagreenate sculpture throughout; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour brown, head and gaster darker than mesosoma.

Measurements

Worker (n = 6): CI 95–107; E 18–27I; EL 0.21–0.27; HL 0.81–1.42; HW 0.77–1.52; ML 1.14–1.62; MTL 0.65–0.93; PpH 0.13–0.23; PpL 0.49–0.73; SI 77–121; SL 0.93–1.18.

Comments

As with several other members of its species-group, M. gibbosus has a wide distribution in mainland Australia, but is relatively uncommon. Based on its appearance, this species seems to be a member of a small clade that also includes M.griseus and M. canus. However, this can not be tested as no specimens were available for sequencing. Specimen data indicate it has been collected from Eucalyptus maculata open forest and from Callitris woodland as well as from a paddock. Queensland Museum material also confirms its presence in mulga and brigalow regrowth. Erect bristly setae all over the head, body, antennal scapes and legs and a thoracic hump in the minor worker are sufficient to identify this species. The major worker has a distinctive, uniformly microreticulate frons.

Etymology

Late Latin gibbosus (‘humpbacked’); adjective in the nominative singular.

Figure 13. 

Melophorus gibbosus sp. n.: major worker paratype (ANIC32-900073–second point from top; end ant) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900031) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, e–f); 0.2 (d).

Melophorus griseus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker from Argyle Diamonds via Kununurra, Western Australia, September 1989, A. T. Postle, Site 15 Melophorus sp. [JDM32-004555] (WAM). Paratypes: 2 minor workers from Gibb River Road turnoff 15°50.096'S, 128°18.664'E, Western Australia, 9 February 2013 (3.40pm), Heterick, B.E., Sample 35: parking area with tall grass nearby, ABRS M21 (WAM).

Other material examined

Western Australia: Gibb River Rd turnoff (Heterick, B.E., B.E. [M217/M218]).

Diagnosis

Melophorus griseus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. griseus the tibiae possess fine, appressed pubescence in addition to stout, socketed, appressed to subdecumbent setae Melophorus griseus differs from M. curtus by the features mentioned above. The Frontal carinae of the minor worker is raised and laminate at the edges, the frontal triangle is narrowly semi-oval, the sides of head are concave below eyes, giving it a bell-shaped appearance and, in profile, the in profile, pronotum and mesonotum form a gentle curve. These features separate it from its likely nearest relative, M. gibbosus.

Minor worker description

Head. Head approximately oval, sides of head divergent towards mandibular articulations; posterior margin of head planar or weakly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight, elevated. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt with indistinct shagreenate sculpture throughout; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation or hollow; node matt with indistinct microsculpture. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour brown, gaster slightly darker than foreparts.

Measurements

Worker (n =1): CI 91; EI 23; EL 0.23; HL 1.10; HW 1.01; ML 1.58; MTL 1; PpH 0.166; PpL 0.62; SI 136; SL 1.40.

Comments

This ant is differentiated from M. canus in lacking the long, silky setae and the dentiform mandible, the mandible in this case being five-toothed. The lack of a thoracic hump also helps to separate the minor worker from the minor worker of M. gibbosus. Most workers have bristly, erect setae on the antennae and tibiae. Workers collected in long grass near Dunham River, Western Australia, were extremely timid solitary foragers among (much more numerous) workers of Iridomyrmex minor, which they resemble in the field. The species is both genetically and morphologically closely related to M. canus but is more restricted in its distribution, being apparently confined to the top end, with collections made in NT, QLD and WA (TERC = ‘Group L’) and the Kimberley region in Western Australia (WAM).

Etymology

Latin griseus (‘gray’); adjective in the nominative singular.

Figure 14. 

Melophorus griseus sp. n.: minor worker holotype (JDM32-004555) frons (a), profile (b) and dorsum (c); distribution map for the species (d). Low resolution scale bars: 0.5 mm (a–c).

Melophorus kuklos Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker from Simpson Gap 23.43S, 133.43E, Northern Territory, 6 October 1972, J. E. Feehan, [ANIC32-900095] (ANIC). Paratypes: major worker from slopes above Baroalba Springs 12.47S, 132.51E, Northern Territory, 13 June 1973, R.W. Taylor, Accession 73.608, [ANIC32-900094] (ANIC); dealate queen and 3 minor workers from c. 5 km S of Tor Rock 11.59'S, 133.05'E, 5 June 1973, Northern Territory, R.W. Taylor, outcrop area, Acc. 73.451 (BMNH); major and minor worker from slopes above Baroalba Springs 12.47S, 132.51E, Northern Territory, 17 November 1972, R.W. Taylor & J.E. Feehan, Euc. savanna, Acc. 72.1006, ANIC ANTS Vial 38.92 (MCZ).

Other material examined

Northern Territory: Baroalba Spring (Taylor, R.W.), Western Australia: Augustus Island.

Diagnosis

Melophorus kuklos is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. kuklos the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the minor worker mesosoma is compact and has an arcuate outline. Melophorus kuklos most closely resembles M. aeneovirens, but in the former, in profile, the clypeus is straight or weakly and broadly convex, and produced over the mandible as a very pronounced ledge. In full-face view, the anteromedial margin of the major and minor worker clypeus is produced as a narrow flange that is distinctly notched or even forked at its midpoint. Also, in contrast to M. aeneovirens, the dorsum of the minor worker mesosoma is strongly arcuate and almost elliptical.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes curved inward in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove generally shallow (NT) but may be more deeply impressed (WA), broadly V or U-shaped; propodeum shining and shagreenate; propodeum uniformly flattened along an oblique trajectory; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node square with rounded angles; node shining and smooth with vestigial sculpture. Gaster. Gaster shining with superficial microreticulation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour dark brown.

Major worker description

Head. Head square; posterior margin of head planar or weakly concave; cuticle of frons matt or with weak sheen, microreticulate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye small (eye length less than 0.2 × length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes curved inward in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal margin entire or weakly indented, or narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth, but equivalent in length to remaining teeth; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly spaced appressed setae. General characters. Colour russet.

Measurements

Worker (n = 4): CI 89–106; EI 16–29; EL 0.18–0.25; HL 0.69–1.48; HW 0.61–1.57; ML 1.02–1.74; MTL 0.54–0.87; PpH 0.12–0.17; PpL 0.52–0.87; SI 72–141; SL 0.86–1.14.

Comments

All but two of the known collections of this compact little member of the M. aeneovirens group have been taken in the NT, although the collection localities range from the far north (Baroalba Spring and Tor Rock in Arnhem Land) to Simpson Gap in the West MacDonnell Ranges, near Alice Springs. The two exceptions are an ant collected on Augustus Island, WA, at a malaise trap (WAM) and a collection from Yampi Island Station, WA (TERC; tentatively this species). Melophorus kuklos is most similar to M. aeneovirens, from which it is distinguished by its more arcuate mesosoma and its strongly produced clypeus, which is bifurcated anteromedially. No specimens were available for sequencing, but its morphology suggests a close relationship with M. aeneovirens. Although ecological data are limited it appears to be catholic in its requirements, samples having been taken from a rocky outcrop, eucalypt savannah and rainforest.

Etymology

Greek kuklos (‘circle’, referring to the species’ outline); noun in the nominative singular standing in apposition to the generic name.

Figure 15. 

Melophorus kuklos sp. n.: major worker paratype (ANIC32-900094) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900095) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, e–f); 0.2 (d).

Melophorus mullewaensis Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from Mullewa, Western Australia, 15 September 1931 [collector unknown] [ANIC32-06621] (ANIC). Paratype: Minor worker on same pin and with same details as holotype (ANIC).

Diagnosis

Melophorus mullewaensis is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. mullewaensis the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Only the (damaged) minor worker of Melophorus mullewaensis is known. This species can be distinguished from all others in its species-complex by its flattened, attenuated pronotum.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex, frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex and protrusive; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity greater than 2:1; erect propodeal setae always absent; appressed propodeal setulae long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node rectangular, vertex blunt, directed posteriad; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster missing in two known specimens. General characters. Colour chocolate.

Measurements

Worker (n = 2): CI 88; EI 25–28; EL 0.25–0.26; HL 1.05–1.18; HW 0.92–1.04; ML 1.91–2.01; MTL 1.13–1.21; PpH 0.17–0.14; PpL 0.80–0.87; SI 144 (one specimen); SL 1.49 (one specimen).

Comments

This ant is known from a single pin of two damaged minor workers collected in the vicinity of Mullewa, Western Australia, very many years ago. These ants resemble the much more common Melophorus aeneovirens but are more gracile and the pronotum is more-or-less planar. Unfortunately the gaster of both specimens is missing. Nothing more is known about the species.

Etymology

Named after the type locality; third declension masculine suffix added to toponym to form an adjective.

Figure 16. 

Melophorus mullewaensis sp. n.: minor worker holotype (ANIC32-06621–top ant) frons (a), profile (b) and dorsum (c); distribution map for the species (d).

Melophorus platyceps Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from Koonamore, South Australia, 24 February 1973, P.J.M. Greenslade, (2) [ANIC32-900117]. Paratypes: 2 major workers on same pin and with same details as holotype (ANIC); 3 minor workers from 31.3 km S of Shearer’s Quarters 141°01'40"S, 34°50'30"E, Millewa South Bore Track, Murray Sunset National Park, Victoria, 14-23 November 2002, C. Lambkin, D. Yeates, N. Starwick & J. Recsei, 2m Sharkey malaise opening in closed mallee [ANIC32-043294] (ANIC); 2 major workers and minor worker from Blyth, N of Adelaide, South Australia, 11 June 1957, B.B. Lowery, 50 ft, mallee scrub, ANIC Ants Vial 22.69 (BMNH); major and 2 minor workers from Blyth, N of Adelaide, South Australia, 28 November 1957, B.B. Lowery, mallee scrub, ANIC Ants Vial 22.68 (MCZ); 3 minor workers from 5 km NW Ketchowla HS, South Australia, 23 January 1975, P.J.M. Greenslade, (5) (SAM); minor worker 2 km N of Wongan Hills, Western Australia, 24 February 1989, B. Heterick, soil, native vegetation, rural environment, 505, 8 MelBH35 (WAM).

Other material examined

South Australia: 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J.M.), 15 km NE Mt Bryan (Greenslade, P.J.M.), 49 km N Minnipa (DEH Surv. 507-KDO-013 [M80/M106]), Brookfield Conservation Park (Shattuck, S.O.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Oraparinna (Greenslade, P.J.M.), Wudinna townsite (Heterick, B.E. [M329]). Victoria: 15 km WNW Yaapeet (Andersen, A.N.), ca. 15 km WNW Yaapeet, Wyperfeld National Park (Yen, A.H.), Murray Sunset Natl. Park, Millewa South Bore Track, 31.1 km S Shearers Quarters (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-043294]). Western Australia: Woolundra Rd. (NW of Doodlakine) (Abensperg-Traun, M. [JDM32-001984]).

Diagnosis

Melophorus platyceps is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). Melophorus platyceps has a very flattened head, but can be separated from several other flat-headed Melophorus by its short maxillary palps which don’t reach the neck, and, in particular, in its more-or-less linear mesosomal dorsum after a weak anterior pronotal incline (when seen in profile). These two features, in particular, distinguish it from the otherwise similar M. tenuis, which belongs to the same species-complex. The metanotal groove is vestigial in the minor worker and weakly impressed in media and major workers, and the anterior clypeal margin weakly convex.

Minor worker description

Head. Head rectangular; posterior margin of head weakly convex; frons coriaceous; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt with indistinct shagreenate sculpture throughout; anterior mesosoma in profile weakly elevated anteriad, thereafter uniformly more-or-less flat with metanotal suture absent or vestigial; erect pronotal setae absent; in profile, metanotal groove a weak or vestigial furrow; propodeum matt or with weak sheen and finely striolate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 2:1; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node square with rounded angles; node weakly shining and faintly striolate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts orange or orange tan, gaster dark brown.

Major worker description

Head. Head square; posterior margin of head planar or weakly concave; cuticle of frons matt or with weak sheen, indistinctly shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set below midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified, or erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum matt or with weak sheen and microreticulate-striolate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 4:3; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node square with rounded angles; node shining and faintly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae, erect setae (present in at least some workers) confined to margin of the sclerite. General characters. Colour as for minor worker.

Measurements

Worker (n = 4): CI 84-115; EI 19-33; EL 0.20-0.29; HL 0.73-1.30; HW 0.62-1.50; ML 1.21-1.83; MTL 0.68-0.98; PpH 0.11-0.21; PpL 0.51-0.72; SI 77-156; SL 0.96-1.16

Comments

On the three-gene tree (Figure 5) this species is sister to M. praesens. This species is unlikely to be mistaken for any other Melophorus because of its combination of an elongate, flattened head, flattened trunk and short palps. Also, like M. nemophilus, this is quintessentially an ant of the southern mallee woodlands, and its range exactly coincides with that of the former species. Label data are minimal, as is so often the case with this genus. The species is depicted in Greenslade 1979, Fig. 15a. Greenslade suggested the ant may be adapted to foraging under bark, and this species was among the most common Melophorus species taken in a recent collection by University of Western Australia researchers using bee-intercept traps on the base of eucalypts in the Avon Wheatbelt district.

Etymology

Compound of Greek platys (‘broad’, ‘flat’) plus Latin -ceps (‘-headed’ [from caput]); adjective in the nominative singular.

Figure 17. 

Melophorus platyceps sp. n.: major worker paratype (ANIC32-900117–top ant) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900117–middle ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus praesens Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from 85 km W of Mabel Creek, South Australia, 8–10 October 1980, P.J.M. Greenslade pt B, 24) [ANIC32-900179] (ANIC); Paratypes: 2 minor workers on same pin and with same details as holotype (ANIC); minor worker from 109.5 km SE Newman, 23°52'59"S, 120°38'31"E, Western Australia, June 1986, S. van Leeuwen & R.N. Bromilow, [JDM32-001483], Curtin University JDM Collection, donated 12 Jan. 2015 (BMNH); minor worker from 85 km W Mabel Creek, South Australia, 8-10 October 1980, P.J.M. Greenslade, Pt A, 23), Melophorus sp. 6 loan ANIC 1991 (MCZ); 3 minor workers from Sandringham, [SW] Queensland, February 1980, P.J.M. Greenslade leg. Morton, (10) (QM); 2 minor workers from 30 km E Poeppel Corner, Simpson Desert, South Australia, 25 August 1977, P.J.M. Greenslade (ANIC32-900083) (SAM); minor and 2 major workers from 24 miles ESE of Broome, 17 April 1963, McInnes & Dowse, 28706, Central & NW Aust. 1963, Series A223 (WAM).

Other material examined

Queensland: 40 km E Cameron Corner (Greenslade, P.J.M.), Sandringham (Morton, S.). South Australia:, 3 minor workers (one broken in two) from Brookfield, South Australia, 29 October 1991, (Shattuck, s. [#2506.6]); 10 km E Mt Ive HS, Gawler Ranges, South Australia, (Greenslade, P.J.M.), Mt Serle Stn, 2.3 km SSE Moosha Bore (Flinders Ra surv REH0501). Victoria: 6.3 km N Hattah (Yen, A.L. [M109]). Western Australia: 8 km N Bullfinch (Heterick, B.E. [M130/M131]), Theda/Doongan, North Kimberley (Cross, A.) [not on map], Derby (Dodd, W.D.), Kojonup (Majer, J.D. [JDM32-001474]), Pardoo Stn turnoff (Heterick, B.E. [M266]), Tutanning, (Perth, A. [JDM32-001480] [major worker – imaged, this work]).

Diagnosis

Melophorus praesens is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. praesens the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Melophorus praesens is almost identical to M. clypeatus but can be distinguished from that species by the less protrusive clypeus in both major and minor workers. Minor workers of Melophorus praesens can be distinguished from those of the similar M. castaneus by the asymmetrical appearance of the vertex and by the overlapping appressed setae on the gaster, and from minor workers of M. rufoniger by their smaller size (M. rufonigerHW of major worker >3 mm, HW of minor worker > 1 mm; M. praesensHW of major worker ≤ 2.3 mm, HW of minor worker < 1 mm) and the less protrusive medial sector of the clypeus.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove deep, ‘V’-shaped, or shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, long, whitish, appressed setae only, erect setae always absent. General characters. Two main colour forms: concolorous chocolate, and orange-tan with chocolate gaster.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head planar or weakly concave; cuticle of frons shining with superficial shagreenation or microreticulation only, or matt or with weak sheen, indistinctly shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye small (eye length less than 0.2 × length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal margin entire or weakly indented; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and microreticulate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and sparse to moderate (1-12); appressed propodeal setae long and closely aligned, creating pubescence, or long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial microreticulation anteriad. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of longish, closely aligned, appressed setae interspersed with short, bristly, erect setae (some distally flattened). General characters. Colour of foreparts tan or reddish chocolate, gaster brown to chocolate.

Measurements

Worker (n = 6): CI 86–108; EI 17–28; EL 0.24–0.38; HL 0.99–2.13; HW 0.85–2.31; ML 1.63–2.65; MTL 0.97–1.60; PpH 0.18–0.25; PpL 0.78–1.31; SI 76–157; SL 1.34–1.76.

Comments

Melophorus praesens has a very broad distribution throughout Australia: records have come from all mainland states except NSW, but it probably occurs there as well. This species sensu lato can be distinguished from others in the M. aeneovirens complex by a combination of its asymmetrical head capsule, the shape of the propodeum and the conformation of the clypeus (not as protrusive as that of the very similar M. rufoniger, and resembling more that found in M. aeneovirens in most specimens). The tibiae completely lack fine, appressed pubescence in the northern topics and desert form, but there may be a few tiny setae, especially at the base of the tibia, that can be seen in some lights, in the southern form. A five-gene tree places this species as sister to M. rufoniger, which it very closely resembles. This ant has mainly been collected in arid and semi-arid areas. In more mesic localities it is replaced by M. aeneovirens. Labels reveal little in the way of additional data, but the species has a generalized morphology typical of the group and probably has habits to match. Collections have been made from a variety of habitats. One specimen hand collected near Pardoo, WA, was active in thundery conditions on a recently burnt plain, while another specimen was hand collected in Bullfinch, WA on red loam soil. Yet another sample was collected at Mt Serle Stn, SA, from a creek line in low rocky hills.

Note: what is here called ‘praesens’ reveals perhaps two forms that can only be distinguished by very subtle differences in the length and appearance of the appressed setae on the tibiae and gaster. Paratypes have been chosen that unequivocally match the holotype (northern/desert form), which has sparse, stout appressed setae on the tibiae and short appressed setae on the gaster that are mostly separated by more than their own length and do not form pubescence. All paratypes have orange-brown foreparts and brown gasters. There is the possibility that the hairier southern form (which has shining, elongate setae on the gaster that may form a weak pubescence, and a few minute appressed setae on the tibiae among rather elongate, fine appressed setae) is genetically distinct, and may constitute a western population of M. curtus, which it closely resembles in general morphology. In some series with dark brown minor workers the metanotal groove is deeply impressed and the propodeum has a marked anterior peak. Specimens have mainly been taken from south-west WA in drier areas and the south-east corner of SA. Further adding to the complication, the specimens from Brookfield (SA) and Junana Rock (WA), are particularly hirsute and have fine pubescence on the mesosoma in addition to the long, fine appressed setae on the gaster. Insufficient specimens have been sequenced (none of indubitable M. curtus) to do more than flag these apparent subtle differences here for future investigation.

Etymology

Latin praesens (‘at hand’); participle in the nominative singular.

Figure 18. 

Melophorus praesens sp. n.: major worker (JDM32-001480) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900117–top ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f). Low resolution scale bars: 1 mm (b, c, e); 0.5 mm (a, d).

Melophorus rufoniger Heterick, Castalanelli & Shattuck, sp. n.

Types

Minor worker (bottom ant) from Koonamore, South Australia, 24-27 February 1973, P.J.M. Greenslade, pitfall traps [ANIC32-066663] (ANIC). Paratypes: media and minor worker on same pin and with same data as holotype (ANIC); media and 2 minor workers from Katarapko island, South Australia, 29 April 1999, Loxton High, River Red Gum Pitfall [ANIC32-046417] (ANIC); 2 minor workers from Whiporie, 55 km s of Casino 29°15'S, 152°27'E, New South Wales, February 1997, SGO. 7-9, ‘Melophorus sp. 1 RTU 78 (ANIC); major and minor worker from Koonamore, South Australia, 24 February 1973, P.J.M. Greenslade, 1), [ANIC32-066641] (BMNH); major and minor worker from WNW Morgan, South Australia, 2 March 1975, P.J.M. Greenslade (leg. R. B. Halliday), (Nest 284) (MCZ); minor and 1 media worker from Cooloola, Noosa River, Queensland, 20 February 1977, P.J.M. Greenslade, (7) (QM); 2 minor workers from Reny Island 34°03'59"S, 140°42'41"E, South Australia, 6 November 1998, Renmark High, Black Box flight intercept [ANIC32-046592] (SAM). 2 minor workers from 15 km ESE Gympie 26°16'S, 152°48'E, Queensland, 2 January 1989, S. O. Shattuck,100m, #1244, Wet sclerophyll, random ground foragers, ANIC ANTS VIAL 77.109 [ANIC32-044509] (WAM).

Other material examined

Australian Capital Territory: Black Mountain (Greaves, T.), Black Mountain (Greaves, T.), Black Mountain (Mercovich, C.), Mt. Pleasant (Lowery, B.B.). New South Wales: 12 mi WSW Boomi (Greaves, T.), 40 km NNW Louth, Lake Mere (Greenslade, P.J.M.), Bogan River (Armstrong, J.), Broken Hill (Lowery, B.B.), Callubri Station, 2 mi from homestead (Greaves, T.), Callubri Station, 2 mi from homestead (Greaves, T.), CSIRO Lake Mere Field Station, near Louth (Bryannah, M.), Elura Mine, Cobar (Greenslade, P.J.M.), Fowlers Gap (Greenslade, P.J.M.), Fowlers Gap (Greenslade, P.J.M.), Fowlers Gap Research Station (Naumann, I.D. & Cardale, J.C.), Gwydir Hwy, 5 km E Warialda (Reichel, H.L.M. [ANIC32-007246]), Lightning Ridge (Lowery, B.B.), Newholme Road, near Armidale (Sakurai, Y.), S. Ita (Greenslade, P.J.M.), Tomago (Jackson, G.P. [ANIC32-015277]). Northern Territory: 200 km NE Alice Springs (Andersen, A.N.), 25 km N Alice Springs (Shattuck, S.O.), 25 km N Alice Springs (Shattuck, S.O.), 27 km SW Katherine (Greenslade, P.J.M.), 5 km S Jabiru, Alligator Rivers area (Greenslade, P.J.M.), Atartinga, NW Alice Springs (Greenslade, P.J.M. [ANIC32-900096]), Bing Bong homestead (Feehan, J.E.), Doyles Ridge (Greaves, T.), Gove, Nhulunbuy (Taylor, R.W. [ANIC32-002773]), Jabiru (Greenslade, P.J.M.), Jabiru (Greenslade, P.J.M.), Johnstons Lagoon (Greaves, T.), Kapalga, Alligator Rivers area (Greenslade, P.J.M.), Koolpinyah (Barrett, C.), Koolpinyah (Hill, G.F.), Kunoth Paddock, near Alice Springs (Greenslade, P.J.M.), Kunoth Paddock, near Alice Springs (Greenslade, P.J.M.), Manbulloo Research Station (Gross, G.), Manbulloo, SW Katherine (Greenslade, P.J.M.), Manbulloo, SW Katherine (Greenslade, P.J.M.), Manbulloo, SW Katherine (Greenslade, P.J.M.), nr Limbunya turnoff (Heterick, B.E. [M222/M223]), slopes above Baroalba Spring (Taylor, R.W. & Feehan, J.E.), slopes above Baroalba Spring (Taylor, R.W. & Feehan, J.E.). Queensland: 15.5 km S Emerald (Greenslade, P.J.M.), 2 km N Charleville (Edwards, E.D. & Fisk, J.H. [ANIC32-007282]), 2 km N Rokeby (Zborowski, P. & Horak, M. [ANIC32-043556]), 30 km SSE Heathlands (Shattuck, S.O.), 35 km SSW of Charleville (Edwards, E.D. & Fisk, J.H. [ANIC32-015215]), 3 km W Batavia Downs (Zborowski, P. & Dressler, W. [ANIC32-043028]), 3 km W Batavia Downs (Zborowski, P. & Calder, A. [ANIC32-042992]), 7 km N Finch Hatton (Shattuck, S.O. [ANIC32-045391]), Blair Athol Mine (Houston, W. [ANIC32-040334]), Burwilla, Cooloola (Greenslade, P.J.M.), Byfield State Forest (Shattuck, S.O. [ANIC32-044921]), Carnarvon Gorge National Park (Shattuck, S.O. [ANIC32-044799]), Clermont (Cudmore, R.A.), Como Scarp, Cooloola (Greenslade, P.J.M.), Cooloola (Plowman), Eulo (Greenslade, P.J.M.), Gold Creek Reserve, Brisbane (Lowery, B.B.), Hann River (Zborowski, P. & Horak, M. [ANIC32-031061]), Irene St., Cairns (collector unknown [ANIC32-015156]), Kabali East, Cooloola (Greenslade, P.J.M.), Kabali West, Cooloola (Greenslade, P.J.M.), Kabali West, Cooloola (Greenslade, P.J.M.), Kirrama (Greenslade, P.J.M.), Musgrave, 17 km W Coleman R Crossing (Eastwood, R. [M115]), near Dimbulah (Taylor, R.W. & Feehan, J.), Noosa River, Cooloola (Greenslade, P.J.M.), Noosa River, Cooloola (Greenslade, P.J.M.), Rainbow Beach, National Park Ranger Station (Shattuck, S.O. [ANIC32-044523]), Teewah Creek, Cooloola (Greenslade, P.J.M.), Teewah Creek, Cooloola (Greenslade, P.J.M.), Townsville (Conlith, S.), Wacol, Brisbane (Lowery, B.B.). South Australia: 15 km NW Blinman, Flinders Ranges (Greenslade, P.J.M. [ANIC32-900097]), 5 km W Geranium (Greenslade, P.J.M.), 8 km W Lameroo (Greenslade, P.J.M.), Blyth (Lowery, B.B.), Blyth (Lowery, B.B.), Buckleboo Homestead, N Eyre Peninsula (Greenslade, P.J.M.), Gawler Ranges (Greenslade, P.J.M); Katarapko Island (General) (Loxton High [ANIC32-046270]), Katarapko Island (General) (Loxton High [ANIC32-046408]), Koonamore (Greenslade, P.J.M.), Koonamore (Greenslade, P.J.M.), Loxton (Kaires, R. [ANIC32-015153]), Nth Moolooloo Stn, 6.7 km SSE (NWFR Survey PUTO2), Reny Island (Renmark High [ANIC32-046604]), Reny Island (Renmark High [ANIC32-046587]), Sturt Vale Homestead (Greenslade, P.J.M.), WNW Morgan (Halliday, R.B.). Victoria: 15 km WNW Yaapeet (Andersen, A.N.), 2 km E Cowangie (Shattuck, S.O.), Chinaman Well, Big Desert (Andersen, A.N.), Heathcote (Lowery, B.B.). Western Australia: 17 km E Invermay Stn (Heterick, B.E. [M227]), 26 mi SSE Karonie (Taylor, R.W.), 7 mi SSE Widgiemooltha (Taylor, R.W.), County Downs Hsd (south boundary) (Heterick, B.E. [M247]), Creek Crossing camp, 54 km W Durack River homestead (Shattuck, S.O.), Dunham River (rest area) (Heterick, B.E. [M213]).

Diagnosis

Melophorus rufoniger is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. rufoniger the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Melophorus rufoniger major and minor workers can be distinguished by their large size (HW > 1 mm in minor workers and > 3 mm in major workers), the asymmetrical vertex in the minor worker and the well-developed and protrusive clypeal flange in both major and minor workers. This species is also predominantly red-and-black compared with the shades of brown or yellow seen in similar species.

Minor worker description

Head. Head approximately oval, sides of head divergent towards mandibular articulations; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons shining with superficial shagreenation or microreticulation only; frons consisting almost completely of appressed setae that may form pubescence (tiny, erect setae, if present, usually confined to ocular triangle). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad, or distinctly concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove deep, ‘V’-shaped, or shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity greater than 2:1; erect propodeal setae always absent; appressed propodeal setulae minute and closely aligned, creating a silvery sheen; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node rectangular, vertex blunt, directed posteriad; in full-face view, shape of petiolar node uniformly rounded, or square with rounded angles; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced, long, whitish, appressed setae only, erect setae always absent. General characters. Colour of foreparts orange to reddish-tan, legs light tan, gaster chocolate.

Major worker description

Head. Head quadrate (i.e., heart-shaped); posterior margin of head strongly concave; cuticle of frons shining and smooth except for piliferous pits, or shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye small (eye length less than 0.2 × length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anterior clypeal margin narrowly convex and protruding anteromedially, clypeal midpoint notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth, but equivalent in length to remaining teeth; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt with indistinct shagreenate sculpture throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum matt or with a weak sheen and indistinctly shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; appressed propodeal setae minute and closely aligned, creating a silvery sheen; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded, or generally rounded with median indentation, or square with rounded angles; node shining and faintly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts reddish- or orange-brown, gaster brown to chocolate.

Measurements

Worker (n = 8): CI 87–109; EI 14–25; EL 0.28–0.47; HL 1.26–3.19; HW 1.10–3.46; ML 2.12–3.59; MTL 1.43–2.30; PpH 0.21–0.47; PpL 0.96–1.65; SI 69–158; SL 1.74–2.39.

Comments

This species, like the preceding one, is widely distributed throughout Australia, although it avoids the wetter south-west corner of WA and similarly cool, moist habitats in SA and Vic. Melophorus rufoniger is on average larger than M. praesens and lighter in colour, predominantly red or orange with a darker gaster. The clypeus is produced well beyond the base of the mandibles, and this feature and the asymmetrical head enable it to be distinguished from other members of its complex except for some morphologically very similar populations of reddish M. curtus, in which case the pilosity of the hind femur must be closely examined. Despite its close physical resemblance to M. praesens, a three-gene tree places this species as sister to M. sulconotus, a quite different-looking species with a distinctively plateau-like pronotum and mesonotum that descends abruptly to the propodeum. (Melophorus sulconotus was not successfully sequenced for the full five genes, so M. rufoniger and M. praesens appear as sisters on the five-gene tree, as might be expected from the morphology.) Melophorus rufoniger has been collected frequently in both red clay soil and yellow soil and also in a variety of vegetation zones. The latter include eucalyptus savanna, sclerophyll woodland, riparian woodland, mallee, Callitris woodland and Melaleuca woodland. One WA worker from Karonie was collected by sweeping, suggesting this species may forage on low vegetation. Given its typical appearance and its environmental adaptability, this species is likely a generalized scavenger.

Etymology

Latin rufus plus niger (‘red-and-black’); adjective in the nominative singular.

Figure 19. 

Melophorus rufoniger sp. n.: major worker paratype (ANIC32-066641–top ant) frons (a), profile (b) and dorsum (c); paratype media worker (ANIC32-046417) frons (d), profile (e) and dorsum (f); minor worker holotype (ANIC32-066663–bottom ant) frons (g), profile (h) and dorsum (i); distribution map for the species (j).

Melophorus sulconotus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (middle ant), Kapalga, Alligator Rivers area, Northern Territory, 7-9 September 1993, P.J.M. Greenslade, 8Aii traps, [ANIC32-900071] (ANIC). Paratypes: 2 minor workers on same pin and with same data as holotype (ANIC).

Other material examined

Western Australia: 4 km E Lake Argyle (Heterick, B.E. [M219]).

Diagnosis

Melophorus sulconotus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. sulconotus the tibiae possess fine, appressed pubescence in addition to stout, socketed, appressed to subdecumbent setae No major worker was available for examination. The chief diagnostic feature in the minor worker is the flattened posterior pronotum and mesonotum which descends steeply to the metanotal groove. This species is restricted to the wetter Northern Kimberley distinct and the far north Northern Territory.

Minor worker description

Head. Head square; posterior margin of head weakly convex; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye small (eye length less than 0.2 × length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight, elevated. Anteromedial clypeal margin broadly and evenly convex and protrusive; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron matt or with weak sheen and microreticulate throughout; anterior mesosoma in profile smoothly rounded anteriad, thereafter pronotum and whole of mesonotum flattened and on same plane as propodeum; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove deep, ‘V’-shaped; propodeum matt or with a weak sheen and microreticulate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae minute and closely aligned, creating a silvery sheen; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour of foreparts orange, legs light tan, gaster dark brown.

Measurements

Worker (n = 2): CI 97–99; EI 19–20; EL 0.27–0.29; HL 1.38–1.55; HW 1.34–1.53; ML 2.24–2.46; MTL 1.47–1.58; PpH 0.22–0.26; PpL 0.86–0.93; SI 120–127; SL 1.71–1.84.

Comments

This rare and rather attractive Torresian species in the M. aeneovirens species-group is known only from the minor and media workers. The profile is distinctive (noted under ‘Comments’ for Melophorus rufoniger). Genetic sequencing indicates the ant may be sister to M. rufoniger. Specimens collected from the Victoria Hwy roadside near Kununurra, Western Australia, decorated their nest with flattened pebbles much larger than the ants.

Etymology

Latin sulcus (‘groove’) plus Neo-Latin notus (‘back’); adjective in the nominative singular.

Figure 20. 

Melophorus sulconotus sp. n.: minor worker holotype (ANIC32-900071–middle ant) frons (a), profile (b) and dorsum (c); distribution map for the species (d). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a).

Melophorus tenuis Heterick, Castalanelli & Shattuck, sp. n.

Type

Holotype minor worker from 1.3 km NE of Morgan River, 15°08'10"S, 126°09'09"E, Western Australia, 20 August 2012, A. Cross; 345m elevation, ethylene glycol pitfall, open savannah [sic] woodland over sandy soil; sp. C [ANIC32-900210] (WAM).

Diagnosis

Melophorus tenuis is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. tenuis the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. In profile, the mesosoma of the minor worker tends to linear in orientation, its dorsal outline straight or describing a weak arc (the mesosternal outline and the dorsum of the mesonotum being weakly convergent to subparallel anteriorly). Only the minor worker of Melophorus tenuis is known. This species can be distinguished from all others in its species-complex its dorsoventrally flattened head, its long maxillary palps (short in the superficially similar M. platyceps) and its weakly sinuous mesosomal outline when seen in profile.

Minor worker description

Head. Head approximately oval, sides of head divergent towards mandibular insertions; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; cuticle of frons with weak sheen, finely shagreenate; in single specimen pilosity of frons consisting exclusively of well-spaced, appressed setae only. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eyes set around midline of head capsule; eye shape elliptical. Antennal carinae straight in full-face view; antennal lobes curved toward antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile flattened, promesonotum on same plane as propodeum; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum shining and shagreenate; propodeum elongate, smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and completely inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node subcuboidal, its vertex bluntly rounded; in full-face view, shape of petiolar node uniformly rounded; node shining and faintly shagreenate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour uniformly dark olive-brown.

Measurements

Worker (n = 1): CI 82; EI 30; EL 0.25; HL 0.99; HW 0.82; ML 1.72; MTL 1.18; PpH 0.16; PpL 0.67; SI 168

Comments

Melophorus tenuis has an appearance somewhat reminiscent of Melophorus attenuipes and Melophorus mullewaensis, but, although it is likely closely related to these taxa, it can be distinguished from them by the much flattened head and the appearance of the femur and clypeus. This ant has been collected from a number of sites in the far north of Australia, but only one minor worker was available for this project. TERC material from WA has been collected from King Edward River, Bachesten Creek, Purnululu NP, Parry Lagoon and the Mitchell Plateau. TERC also holds specimens from Bradshaw Stn, Barunga, Nitmuluk NP, Bullo Gorge and Kakadu in the NT.

Pitfall-trapped specimens collected by Adam Cross in Doongan and Theda Stations in the Kimberley were found in four study plots on shallow, sandstone-derived soils overlying Pentecost sandstone. The vegetation was open savannah woodland dominated by Eucalyptus tetradonta and E. miniata over shrubs and low annual grasses. Three of the four plots were near the Morgan River, and the fourth was on Noongallah Creek (A. Cross, pers. comm.). The holotype is one of the Morgan River specimens from that project.

Etymology

Latin (‘thin’, ‘slender’); adjective in the nominative singular.

Figure 21. 

Melophorus tenuis sp. n.: minor worker holotype (ANIC32-900210) frons (a), profile (b) and dorsum (c); distribution map for the species (d). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a).

Melophorus teretinotus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from Ethel Creek, Western Australia, February 1996, F. K. Sengarayar [JDM32-004552] (WAM). Paratypes: minor worker on same pin and with same data as holotype (WAM); minor worker from Barrow Island, 20°47'38'S, 115°36'24"E, Western Australia, 24 April, 2005, S. Callan, Suction RI pit AL [JDM32-004553] (ANIC).

Other material examined

Western Australia: Argyle Diamond Mine via Kununurra (Postle, A. [JDM32-004554]), Barrow Island (N. Gunawardene/C. Taylor [M314]).

Diagnosis

Melophorus teretinotus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded), and the M. aeneovirens species-complex (in full-face view, psammophore ranged along or just above anterior margin of clypeus and following the curve of the margin; anterior margin of clypeus broadly medially produced, and often with central notch that may be deeply impressed, but is never acuminate at its midpoint; metatibia with maximum of two rows of preapical spines). In M. teretinotus the tibiae possess stout, socketed, appressed to subdecumbent setae only, with fine, appressed pubescence lacking. The minor worker only is known. Melophorus teretinotus cannot be mistaken for any other Melophorus: the mesosoma is strongly arched, smooth and glabrous, the mesonotum and propodeum are confluent and the metanotal groove is completely lacking.

Minor worker description

Head. Head square; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae concave; frontal lobes curved inward in front of antennal insertion. Anteromedial clypeal margin narrowly convex and protruding, clypeal midpoint distinctly notched; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove absent; propodeum shining and uniformly striolate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour brown, gaster slightly darker than foreparts.

Measurements

Worker (n = 4): CI 82–85; EI 26–30; EL 0.21–0.25; HL 0.83–1.16; HW 0.68–0.98; ML 1.38–1.64; MTL 0.62–0.79; PpH 0.10–0.17; PpL 0.68–1.04; SI 127–149; SL 1.02–1.25.

Comments

The odd outline of the minor worker of this species makes it impossible to confuse it with any other Melophorus. The absence of the metanotal groove is distinctive, and the shining, broadly expansive pronotum and mesonotum smoothed over into a deeply declivitous propodeum brings to one’s mind the curve of a snail shell. Only the minor worker has so far been recognized. All records have come from WA, where it appears occasionally in collections from the Kimberley and Pilbara region on the mainland and from Barrow Island, but the species is also likely to occur in the NT. The ecology of this ant is not known. Attempts to sequence its DNA have achieved only limited success with only the wingless gene successfully amplifying. Its closest relation is M. praesens, based on pairwise divergence of the Wg gene (1.8% pairwise divergence).

Etymology

Latin terete (‘cylindrical and tapering’) plus Neo-Latin notus (‘back’); adjective in the nominative singular.

Figure 22. 

Melophorus teretinotus sp. n.: minor worker holotype (JDM32-004552) frons (a), profile (b) and dorsum (c); distribution map for the species (d). Low resolution scale bars: 0.5 mm (a–c).

Melophorus bagoti complex

This complex consists of two widespread and spectacular, large Melophorus that are often encountered in drier habitats throughout Australia. Melophorus bagoti has attracted a lot of research interest as its habits and its appearance make it a relatively easy research subject compared with smaller, less easily identifiable species. The complex is identifiable by the conformation of the clypeus and the appearance of the clypeal psammophore.

The five-gene phylogenetic trees reveal good branch support for the M. bagoti complex as a monophyletic group and as sister to the M. nemophilus complex (see figures 3 and 4, respectively). In respect of M. bagoti, intraspecific pairwise divergences for the genes COI and H3 were considerably higher than for all other Melophorus species, the difference being attributed to sample M143. This specimen has an iridescent black gaster (orange or greyish-orange and non-iridescent for the other samples). Despite the high pairwise divergences for the COI and H3 genes, M143 not was not split from the other bagoti, being monophyletic within the remaining samples, and the Wg gene shows it fitting comfortably into the clade (next to the more typical M220) that includes the sequenced samples for this species. More specimens are needed before there is any thought of assigning this spectacular form a new species status.

Melophorus bagoti Lubbock

Melophorus bagoti Lubbock 1883: 52, pl. 2, figs 1–10. Type. Syntype major worker without an original label [BMNH] (examined: AntWeb image of BMNH specimen BMNH(E)1016283, CASENT0903260).

Camponotus cowlei Froggatt. Froggatt, W. W. (1896). Honey ants. pp. 385–392 In: Spencer B (Ed.) Report on the work of the Horn Scientific Expedition to Central Australia. Melbourne: Melville, Mullen & Slade Part 2 Zoology. [p. 387 pl. 27] (combination as Melophorus cowlei by Wheeler 1908:388; combination as Camponotus (Myrmophyma) cowlei by Emery 1925:110; junior synonym of Melophorus bagoti by Clark 1930:22; combination and valid species as Camponotus cowlei by Taylor and Brown 1985:112). Types. Syntype major workers (assumed) and queen on separate pins, without collection data [AMS]. [Not seen] Syntype worker(s), queen(s), male(s), Spencer Gorge, McDonnell Ranges, Northern Territory [museum unknown]. Rev. comb. (Note. The material includes the discoloured head and pronotum of a major worker and a worker gaster that have been glued to a newish-looking card rectangle, but the gaster does not appear to belong to that pin as it is shining and new in appearance, and may not even be that species. All three ants are labeled with their caste, surname and initials of Froggatt and date (1895) (label 1), and the scientific name (‘Camponotus cowlei Froggatt’) (label 2). There is no mention of the collection locality. A gelatin capsule holds broken fragments of legs.)

Other material examined

New South Wales: 40 km NNW Louth, Lake Mere (Greenslade, P.J.M.), 40 km NNW Louth, Lake Mere (Greenslade, P.J.M.), CSIRO Lake Mere Field Station, north Louth (Bryannah, M.), Sturt National Park (Greenslade, P.J.M.). Northern Territory: 18 km E The Granites (Morton, S. & Greenslade, P.J.M.), 25 km N Alice Springs (Shattuck, S.O.), 25 km SSW The Granites, Tanami Desert (Morton, S. & Greenslade, P.J.M.), 35 km SW The Granites, Tanami Desert (Morton, S. & Greenslade, P.J.M.), 28 km WbyS Docker River (Feehan, J.E.), Glen Helen (Shattuck, S.O.), 61.5 km E Kalkarindji (Heterick, B.E. [M220]), Avon Downs (Colles, D.H.), Barry Caves (Feehan, J.E.), Batchelor (Hill, G.F. [ANIC32-039541]), Ellery Ck., Big Hole, West Macdonnells NP (Shattuck, S.O. [ANIC32-029215]), Kings Creek Station (Donellan, S.), nr Limbunya turnoff (Heterick, B.E. [M224]), Mataranka (Greaves, T), Rabbit Flat near Tanami (Wearne, K), Ti Tree, 170km N Alice Springs (Hiddins, L.). Queensland: ‘Gumbardo’ (Beutel, T.), ‘Gumbardo’ (Beutel, T.), ‘Gumbardo’ (Beutel, T.), ‘Gumbardo’ (Beutel, T.), Holts Creek, 8 km N Musselbrook Camp (Naumann, I. D.), ‘Merigol’ (Beutel, T.), ‘Merigol’ (Beutel, T.), Mica Creek, Mount Isa (Burwell, C. J.), 13 km from S-bend on Plum Pudding Track (Lemann, C. [ANIC32-035469]), 15 mi S Kamilaroi Homestead (Dowse, J.E.), Mt. Isa (Weatherill, L.). South Australia: 14.5 km W Wallatinna HS (Pitjantjatjara Lands Survey [M89/M105]), 18 mi W Mt. Morris (McInnes & Dowse), 25 mi W Mt. Morris (McInnes & Dowse). Western Australia: 10 km NE Woree Hill (Heterick, B.E. [M180/M181/M182]), 11 km E Willare Bridge (Heterick, B.E. [M246]), 12 mi N Wittenoom (McInnes & Dowse), 12 mi S Cardawan Homestead, SSW Mundiwindi (McInnes & Dowse [ANIC32-900069]), 14 km E Roebuck Plains RH (Heterick, B.E. [M187]), 150 km SW Giles Meteorological Station (Heatwole, H.), 16 km SbyW Onslow (Feehan, J.E.), 26 mi NE Paynes Find on Sandstone Road (Douglas, A.M. & M.J.), 27 km SE Newman (Britton, E.B.), 34 mi ENE Broome (McInnes & Dowse), 47 km E Fitzroy Crossing (Heterick, B.E. [M235]), 50 km N Carnarvon (Morton, S.R. [ANIC32-900070]), 56 mi WSW Mt. Gordon, Browne Range (McInnes, R. & Dowse, J.), 68 km S Newman (Britton, E.B.), 70 km N Halls Creek (Heterick, B.E. [M211]), 74 km EbyN Cosmo Newberry (Feehan, J.E.), 85 km E Meentheena OC (CALM Pilbara Survey [JDM32-004588]), Alpha Is., Monte Bello Islands (Campbell, T.G. [ANIC32-039538]), Argyle Diamonds via Kununurra (Postle, A.T. [JDM32-004532]), Broome (Weatherill, L.), Derby (Campbell, J.G.), Derby (Marchant [JDM32-004536]), Garden Well, 9 km SWbyS Mt. Phoenix (Feehan, J.E.), Jigalong (Hickmer, J.), Little Sandy Desert (Guthrie N. A. [M143]), Marillana Station (Dunlop, J.N. [JDM32-004535]), Nita Downs turnoff (Heterick, B.E. [M262]), Tropicana Minesite (Summerhayes, J. [JDM32-004587]), Well 31, Canning Stock Route between Meekatharra and Billiluna Pool [Collector unknown], Willare Bridge (Heterick, B.E. [M190]), Willie Creek turnoff (Heterick, B.E. [M276]), Windjana Gorge National Park (Ward, P.S.).

Diagnosis

Melophorus bagoti is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded). The ant is also placed as a member of the M. bagoti complex because of the acuminate appearance of the midpoint of the anterior clypeal margin. In full-face view, the psammophore occurs as a row of long, thick setae set slightly above the anterior clypeal margin. Melophorus bagoti has five rows of preapical tibial spines on the metatibia, and this distinguishes it from its sister, M. gracilipes, and all other Melophorus.

Minor worker description

Head. Head square or rectangular, tending to trapezoid; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin convex, weakly acuminate anteromedially; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron uniformly shagreenate to moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle or bluntly angulate; length ratio of propodeal dorsum to its declivity about 2:1; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node a broadly right-angled triangle, node with steeply declivitous posterior face; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster smooth and glossy or shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae, erect setae (present in at least some workers) confined to margin of sclerite. General characters. Colour mostly uniformly deep orange, but some workers with foreparts and appendages orange, and gaster black with blue-green iridescence.

Major worker description

Head. Head horizontally rectangular, broader than wide; posterior margin of head planar or weakly convex; cuticle of frons ranging from matt or with weak sheen, indistinctly shagreenate through to shining with superficial shagreenation or microreticulation; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anterior clypeal margin convex, acuminate anteromedially, margin entire; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae long (i.e., longer than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and shagreenate, or matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 3:2 and 4:3; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node a broadly right angled triangle, node with steeply declivitous posterior face; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae, erect setae (present in at least some workers) confined to margin of the sclerite. General characters. Colour as for minor worker.

Measurements

Worker (n = 8): CI 99–118; EI 16–22; EL 0.30–0.52; HL 1.41–2.81; HW 1.39–3.33; ML 2.66–4.59; MTL 1.91–3.01; PpH 0.32–0.47; PpL 1.23–1.73; SI 81–147; SL 2.04–2.71.

Comments

Melophorus bagoti is the Melophorus with which the average layperson from the drier rural areas is probably best acquainted because of its bright colour and its size. The size alone makes this species unmistakable except for M. gracilipes, from which it can be distinguished by the presence of five rows of tibial spurs (compared with the normal two rows in the latter species). Melophorus bagoti has been recorded from all mainland Australian states except Victoria, but appears to be most common in the NT and WA. A number of samples of the taxon have been sequenced, and these reveal a monophyletic group (see above discussion of the complex).

Syntype specimens (at least two) for ‘Camponotus cowlei’ have been seen. Although very badly damaged, sufficient of the ants remain, including the all-important head capsule and spinous tibiae, for the identity of the species not to be in doubt. ‘Camponotus cowlei’ therefore reverts to its previous synonym under the genus Melophorus.

As discussed in the Introduction, this ant has been the focus of a number of studies that look at orientation in desert ants, but its thermophilic aspects and nest structure have also gained attention (see references in the Introduction): along with Melophorus perthensis, this is the best known and most thoroughly researched Melophorus. In drier regions M. bagoti workers are frequently seen scurrying rapidly over the ground surface foraging for seeds and carrion. In the Kimberley, the principal author also saw many workers climbing over a small shrub when it was in flower, seeking nectar.

Figure 23. 

Melophorus bagoti Lubbock: BMNH major worker syntype (CASENT0903260) frons (a), profile (b) and dorsum (c); non–type major worker (ANIC3-900190–top ant) frons (d), profile (f) and dorsum (i); non–type minor worker (ANIC3-900190–bottom ant) frons (e), profile (g) and dorsum (h); Melophorus bagoti workers and reproductives at nest entrance (photo credit: A. J. Narendra) (j); distribution map for the species (k). Low resolution scale bars: 2 mm (f, g, h, i); 0.5 mm (d, g).

Melophorus gracilipes Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant-slightly damaged) from Yamarna Homestead 28°10'S, 123°40'E, Western Australia, 16 December 1996-30 January 1997, S. Richardson, Acacia woodland with spinifex, sandy loam [ANIC32- 032240] (ANIC). Paratypes: major worker and media worker on same pin and with same details as holotype (ANIC); 2 media workers from 55 miles E of Wiluna, Western Australia, 10 October 1969, McInnes & Dowse (ANIC); major worker and 2 minor workers from Murchison River, Western Australia, ‘Melophorus bagoti Lubbock, Det. J.J. McAreavey, 7 January 1960 [sic] [these specimens can easily be distinguished from M. bagoti by the the two rows of spines on the metatibia-BEH] (BMNH); 2 media workers from 10 km SE Karonie, Western Australia, 9 November 1969, Key’s field notes. Trip 163, Stop 19405.6, ground strays, evening, sclerophyll wood., R.W. Taylor (MCZ); Major worker and minor worker from 30 km S of ‘The Overlander’, Western Australia, 20 March 1987, B. Heterick, soil, native vegetation, rural environment, 183, 8MelBH1 (WAM); 2 minor workers from Rabbit Proof Fence Road 30°26'57"S, 118°31'13"E, Western Australia, 21 November 2009, Heterick, B.E., Laterite sandplain, proteaceous heathland with small trees , by hand, early pm [JDM32-004618] (WAM).

Other material examined

Western Australia: 100 km E Wiluna (Forrest, J.), 10 mi SE Karonie (Taylor, R.W.), 11 mi E Meekatharra (McInnes & Dowse), 13 mi SE Giles (McInnes & Dowse), 16 mi S Leonora (McInnes & Dowse), 16 mi W Coonana (Key, K.), 18 mi SE Agnew (McInnes & Dowse), 30 km S of ‘The Overlander’ (Heterick, B.E. [JDM32-001951]), 30 mi E Paynes Find on Sandstone Road (Douglas, A.M. & M.J.), 31 mi SW Mundiwindi (McInnes & Dowse), 4 mi W Mt Charles (McInnes & Dowse), 55 mi E Wiluna (McInnes & Dowse), 60 km N Ajana (Upton, M.S.), 7 mi WSW Manunda Road House (McInnes & Dowse), Ethel Creek (Varris, P.A.), G. J. Rd, 108 km E Carnarvon (Heterick, B.E. [M310]), Geeraning Rock (Heterick, B.E. [JDM32-001950]), Kanka water hole, near Warburton (Heatwole, H. & Greenslade, P.J.M.), Lyndon River (Mercer, R.), Mardathuna Rd turnoff (Heterick, B.E. [M08]), Meekatharra (Mercovich, C.), Mulga, NE Goldfields (Pringle, H.J.R. [ANIC32-029629]), Mullewa, Murchison River (Greaves, T.), nr Pamellia Hill (Heterick, B.E. [M178]), Pannawonica Hill (Bokhari, F. [M150]), Rabbit Proof Fence Rd. (Heterick, B.E. [JDM32-004618]), Sandstone Rd turnoff (Heterick, B.E.[M168/M169/M170]), Tardun (Mercovich, C.), Wiluna, Yamarna Homestead (Richardson, S.).

Diagnosis

Melophorus gracilipes is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded). The ant is also placed as a member of the M. bagoti complex because of the acuminate appearance of the midpoint of the anterior clypeal margin. In full-face view, the psammophore occurs as a row of long, thick setae set slightly above the anterior clypeal margin. Unlike its sister species, M. bagoti, M. gracilipes has just two rows of preapical tibial spines on the metatibia.

Minor worker description

Head. Head approximately oval, sides of head divergent towards mandibular articulations; posterior margin of head extended posteriad as a convex, sloping surface with a slight medioccipital protuberance; frons matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex, or straight, convergent posteriad; frontal lobes curved toward antennal insertion. Anteromedial clypeal margin convex, weakly acuminate anteromedially; clypeal psammophore set below midpoint of clypeus, or set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and uniformly striolate; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node a broadly right angled triangle with steeply declivitous posterior face; in full-face view, shape of petiolar node uniformly rounded, or square with rounded angles; node shining and faintly striolate and microreticulate. Gaster. Gaster shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour variable, pale yellow to brown.

Major worker description

Head. Head square; posterior margin of head planar or weakly convex; cuticle of frons matt or with weak sheen, microreticulate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye small (eye length less than 0.2 × length of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; roughly ovoid, eye narrowed posteriad. In full-face view, frontal carinae straight or weakly convex, or straight, convergent posteriad; frontal lobes straight in front of antennal insertion, or curved inward in front of antennal insertion. Anterior clypeal margin convex, acuminate anteromedially, margin entire; clypeal psammophore set below midpoint of clypeus, or set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen, shagreenate on pronotum and dorsum of mesonotum, otherwise microreticulate; anterior mesosoma in profile broadly convex, or convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and finely striolate and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node narrowly conical, vertex sharply defined, or a broadly right angled triangle; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly striolate and microreticulate. Gaster. Gaster shining with superficial microreticulation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour concolorous light orange or russet with brown gaster.

Measurements

Worker (n = 8): CI 101–120; EI 15–21; EL 0.29–0.44; HL 1.36–2.54; HW 1.38–3.04; ML 2.44–4.11; MTL 2.47–2.84; PpH 0.21–0.47; PpL 1.04–1.70; SI 89–153; SL 2.11–2.69.

Comments

Superficially, this large species resembles large members of the M. aeneovirens complex, but the appearance of the clypeus is sufficient to place it in the M. bagoti complex, and genetic sequencing data confirms this placement. The ant can easily be distinguished from M. bagoti by its more gracile appearance and the presence of two rows of preapical spines on the metatibia (five rows in M. bagoti). As with M. bagoti, the colour of the gaster in this taxon can vary from yellowish orange and concolorous with the rest of the ant to an iridescent black, with various shades in between. (In the case of M. bagoti, nest series of the most strikingly bicoloured ants seem to be of the one colouration, but workers of other nests can nonetheless show variation in colour between light orange gaster and blackish-orange gaster morphs). A specimen of M. gracilipes collected in the Pilbara had the iridescent black gaster, but unfortunately the genetic similarity of this form compared with other, lighter-coloured morphs could not be tested due to poor DNA quality.

Melophorus gracilipes is definitely an ant of the arid and semi-arid areas, and is absent from the wetter parts of the southern coastline. On the mainland all records have come from WA, although it likely also occurs in western parts of the NT and SA. As with other common species in the M. aeneovirens species-group, M. gracilipes has been found in a wide range of phytogeographic zones including hummock grasslands, mulga woodlands, acacia woodlands with spinifex, and sclerophyll woodlands. Red clay soil seems to be a favoured substrate for its nests. This species is a scavenger: a couple of workers hand collected near Pamellia Hill, WA, were carrying a dead grasshopper.

Etymology

Latin gracilis (‘slender’) plus pes (‘foot’); adjective in the nominative singular.

Figure 24. 

Melophorus gracilipes sp. n.: major worker paratype (ANIC32-032240–top ant) frons (a), profile (b) and dorsum (c); minor worker (ANIC32-032240–bottom ant) holotype frons (d), profile (e) and dorsum (f); distribution map for the species (g).

Melophorus nemophilus complex

The Melophorus nemophilus complex consists of one temperate area species that forages on trees as well as the ground. The high placement of the clypeal psammophore makes it unique among its nearest relatives. Phylogenetically the M. nemophilus complex is monophyletic and sister to the M. bagoti complex (see Figure 3).

Melophorus nemophilus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype media worker (top ant) from 17 miles N of Colona HS, South Australia, 23 October 1960, McInnes & Dowse, Series A 336 [ANIC32-900077] (ANIC). Paratypes: 2 major workers on same pin and with same details as holotype (ANIC); 3 minor workers from 31.1 km S of Shearer’s Quarters 141°01'40"S, 34°50'30"E, Millewa South Bore Track, Murray Sunset National Park, Victoria, 14-23 November 2002, C. Lambkin, D. Yeates, N. Starwick & J. Recsei, 2m Sharkey malaise opening in closed mallee [ANIC32-043297] (ANIC); major worker, 2 media workers and a minor worker from 15 km WNW Yaapeet 32°42'S, 141°52'E, Victoria, 13 January 1980, 1500 hrs, A. N. Andersen, Melophorus (BMNH); 2 minor workers from Cambrai, South Australia, 4 February 1972, P.J.M. Greenslade, dune IIb (MCZ); minor worker from 10 km E Mt Ive HS, Gawler Ranges, South Australia, 21 October 1980, P.J.M. Greenslade, (1) (MCZ); minor worker from 10 km E Mt Ive HS, Gawler Ranges, South Australia, 22 October 1980, P.J.M. Greenslade, A2 Sa (SAM); media worker from Cambrai, South Australia, 20 January 1972, P.J.M. Greenslade, dune III (SAM); minor worker from Junana Rock 33.23S, 123.24E, 9 km NW of Mt Ragged, Western Australia, 26 October 1977, R.W. Taylor, 77.667 day strays (WAM).

Other material examined

South Australia: Callanna Bore, Callanna Stn (Stony Desert survey), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Ferries McDonald NP (Mathews, E. G [M116]), Keith, 5 km W Mt. Rough, Coorong (Greenslade, P.J.M. [ANIC32-900078]), near Mt. Westall (Taylor, R.W., Bartell, R.J. & Lowery, B.B.), Poochera (Taylor, R.W. & Bartell, R.J.), Scorpion Springs CP, 6.3 km S Pine Hut Soak (Forrest, J. [M91]), Wudinna townsite (Heterick, B.E. [M334]). Victoria: Little Desert Nat. Pk., Eastern Block, Dahlenburgs Mill Track, 17.8 km S Nhill (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-030801]), Wyperfeld National Park, Murrayville Track, 45.2 km SSE Murrayville (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-030935]). Western Australia: 28 mi SbyW Balladonia Motel (Taylor, R.W.); media worker from Junana Rock (Taylor, R.W.).

Diagnosis

Melophorus nemophilus is a member of the M. aeneovirens species-group (in full-face view, the anterior clypeal margin convex, apron-like and covering whole or part of the retracted mandible, except in M. nemophilus, the medial clypeal sector often produced so that it is protrusive when seen in profile; the psammophore frequently with coarse and well-separated ammochaetae, these always placed on or just above anterior margin; in profile, the propodeum elongate and oblique or broadly rounded) but is placed in its own, monotypic species-complex. Uniquely for this group, the setae of the clypeal psammophore are fine and placed at around the midpoint of clypeus, and the anterior margin of the clypeus is a moderately flattened curve in all workers and does not cover the base of the mandibles. The ant has five to seven mandibular teeth, the major worker having the same mandibular structure as minor worker, and, in profile, the mesosoma is long and gracile, with an obliquely descending propodeum. Molecular data support the placement of M. nemophilus as belonging to a unique complex within the broader M. aeneovirens species-group.

Minor worker description

Head. Head rectangular; posterior margin of head strongly convex; frons matt or with weak sheen, shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set around midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five to seven mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile convex anteriad, mesonotum often slightly overlapping pronotum, mesosoma planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae always absent; appressed propodeal setulae long and separated by at least own length; propodeal spiracle situated at least twice its width from the declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth with vestigial sculpture. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour light brown to blackish, usually concolorous, but gaster may be darker.

Major worker description

Head. Head square; posterior margin of head planar or weakly concave; cuticle of frons shining with superficial shagreenation or microreticulation only; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, eyes set at midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five to six mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately aligned vertically or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile convex anteriad, mesonotum overlapping pronotum, planar or slightly sinuate posteriad; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum shining and shagreenate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour of foreparts orange or brownish-orange with dark brown gaster.

Measurements

Worker (n = 8): CI 96–123; EI 17–30; EL 0.25–0.40; HL 0.86–1.94; HW 0.83–2.38; ML 1.65–2.77; MTL 1.25–1.83; PpH 0.16–0.33; PpL 0.72–1.18; SI 77–94; SL 0.78–1.83.

Comments

This common, gracile species is intermediate in appearance between the M. bagoti complex and the M. aeneovirens complex. Limited sequencing data suggests the ant forms a monotypic complex basal to M. bagoti and M. gracilipes. Morphologically, this species is readily distinguished from others in the M. aeneovirens group by the high placement of the clypeal ammochaetae on the clypeus. Melophorus nemophilus is an arid or semi-arid resident of the southern states, and has been recorded from SA, Victoria and WA. The species may also occur in southwestern NSW, but is most probably absent from QLD and Tasmania. Most samples have been collected from remote areas in dunes, mallee woodland and spinifex and mallee woodland. The species most probably derives much of its nutriment from carrion, honeydew and nectar. A photograph by Ajay Narendra shows two minor workers carrying the corpse of a membracid bug while a major worker looks on (Fig. 6). Interestingly, this very gracile species can climb and forages on trees: the senior author of this paper has seen workers of M. nemophilus scurrying along smooth-trunked eucalypts near Norseman, WA, and workers have been taken in malaise traps in Little Desert N P, Murray Sunset N P and Wyperfeld N P in mid-western and northern Victoria.

Etymology

Latin nemus (‘forest’) plus Neo-Latin philus (‘attracted to’); noun in the nominative singular standing in apposition to the generic name.

Figure 25. 

Melophorus nemophilus sp. n.: media worker holotype (ANIC32-900077–top ant) frons (a), profile (b) and dorsum (c); non–type minor worker (ANIC32-030935) frons (d), profile (e) and dorsum (f); Melophorus nemophilus minor and major worker at bait (photo credit: A. J. Narendra) (g); distribution map for the species (h). Low resolution scale bars: 1 mm (b, c); 0.5 mm (e, f).

Melophorus anderseni species-group

This small group of species is characterized by at least two distinctive apomorphies; namely, short, six-segmented maxillary palps with a strongly acuminate final segment and absent metatibial spur. At least one member is a stealth raider of northern meat ant (Iridomyrmex sanguineus) colonies. No specimens of this species-group were available for sequencing.

Melophorus anderseni Agosti

Melophorus anderseni Agosti 1997: 163, figs 4, 5 (w.q.)

Types

Holotype minor worker, paratype minor workers male and queen, TERC site, Darwin, Northern Territory [ANIC] [CASC] (examined: ANIC holotype (middle ant) CASENT0172008, paratype minor worker CASENT0172007 on the same pin, one worker of Iridomyrmex sanguineus on the same pin as holotype and paratype with a label indicating association of the two species, ANIC paratype queen and two minor workers CASENT0172009, AntWeb image of paratype male [CASC] CASENT0173921.

Other material examined

Northern Territory: Darwin (Shattuck, S.O. [ANIC32-066666]), Mudginberri (Andersen, A.N. [ANIC32-066653]).

Diagnosis

Melophorus anderseni is a member of the M. anderseni species-group (maxillary palp segments short [not reaching neck sclerite], narrow and terminating in a subulate [awl-shaped] segment; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers [except chrysus], and four to six teeth in minor worker). This species is distinguished from three other members of the group by having a thick, rectangular or quadrate petiolar node in the minor worker, the anterior clypeal margin broadly convex and protrusive; the clypeal psammophore located below the midline of the clypeus (major worker) or near its anterior margin (minor worker) and in having the antennal scape of minor worker devoid of erect setae. The species is confined to northern Australia.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head planar or weakly convex; frons matt or with weak sheen, shagreenate; frons consisting almost completely of appressed setae that may form pubescence (tiny, erect setae, if present, usually confined to ocular triangle). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight or weakly convex; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly and evenly convex and protrusive; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Four to five mandibular teeth in minor worker; mandibles narrow, strap-like, internal and external margins parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove a weak or vestigial furrow; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 1:1; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length < than 0.50 × height of propodeum). Petiole. In profile, petiolar node cuboidal, rounded above; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster shining with superficial microreticulation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour reddish-brown, gaster slightly darker.

Major worker description

Head. Head square; posterior margin of head planar or weakly convex; cuticle of frons shining and smooth except for piliferous pits; pilosity of frons a mixture of well-spaced, distinctly longer erect and semi-erect setae interspersed with shorter decumbent setae. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae distinctly concave, frontal lobes curved toward antennal insertion. Anterior clypeal margin broadly and evenly convex; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Mandibular teeth in major worker always four; mandibles narrow, strap-like, internal and external borders parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and1:2; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node narrowly conical, vertex sharply defined; in full-face view, shape of petiolar node generally rounded with median indentation; node shining and faintly shagreenate-microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour dull orange, gaster brownish-orange.

Measurements

Worker (n = 2): CI 98–114; EI 19–24; EL 0.25–0.32; HL 1.06–1.45; HW 1.04–1.65; ML 1.76–1.94; MTL 1.28–1.40; PpH 0.16–0.19; PpL 0.69–0.78; SI 73–135; SL 1.20–1.39.

Comments

Only a few collections of this social parasite of Iridomyrmex sanguineus have been taken, and the description of the worker by Agosti (1997) is in informal, telegraphic style, and is characterized more formally here for the first time. The behavior of M. anderseni in raiding nests of I. sanguineus has been well documented by the same author (Agosti 1997). TERC material has been taken in Kakadu, Kidman Springs, the Ranger Uranium Mine lease (NT), Mt Isa and Tin Camp Creek (QLD). All ANIC collections have been taken in the NT, but the ant may also occur in the Kimberley region of WA (at least) where populations of its host also occur. The apparent rarity of the species may be due to under collection because of its very specialized habits. Melophorus anderseni has several apomorphic characters shared only by the following species (notably very short palps and an absent metatibial apical spur), but its position within the genus as a whole is uncertain in the absence of genetic sequencing. However, the morphology suggests it is not close to the M. aeneovirens group. A possible close relationship with the M. fieldi group and, in particular, the M. fieldi complex is indicated by the presence of an anteromedian dorsal lip or protuberance in the queen (though not the workers).

Figure 26. 

Melophorus anderseni Agosti: non–type major worker (ANIC32-066653) frons (a), underside of head showing palps (b), profile (c) and dorsum (d); non–type minor worker (ANIC32-066666) frons (e), profile (f) and dorsum (g); distribution map for the species (h).

Melophorus andersenioides Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (bottom ant) from 40 miles N of Warren, New South Wales, 23 December 1963, B.B. Lowery, red soil, ANIC ANTS VIAL 68.156 [ANIC32-900082] (ANIC). Paratypes: Major worker and minor worker on same pin as holotype (ANIC); 2 media and a minor worker from Grantham, Queensland, 24 January 1957, B.B. Lowery, dry sclerophyll, ANIC ANTS VIAL 68.209 (BMNH); 3 major workers, media worker and minor worker from Warwick, Queensland, 4 January 1966, B.B. Lowery, Red soil, hilly, sav. woodland, edge of I. detectus nest, morning, R28 (MCZ); minor worker and major worker from Grantham, Queensland, 24 January 1957, B.B. Lowery [ANIC32-900081] (QM); major worker from ROC lease, Eneabba, Western Australia, 10-16 April 1997, L. Bisevac/B.E.Heterick, Plot 77AS, pitfall traps [JDM32-002001] (WAM); 2 minor workers and major worker from Nerren Nerren Stn 27°00’s, 114°32’e, Western Australia, 26 September-19 October 1994, M.S. Harvey/J.M. Waldock, NE4 wet pits, WAQM/CALM survey, Carnarvon Basin [JDM32-002002] (WAM).

Diagnosis

Melophorus andersenioides is a member of the M. anderseni species-group (maxillary palp segments short [not reaching neck sclerite], narrow and terminating in a subulate [awl-shaped] segment; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers [except chrysus], and four to six teeth in minor worker). This species is distinguished from three other members of the group by having a thick, rectangular or quadrate petiolar node in the minor worker, the anterior margin of clypeus weakly convex, the clypeus folded back and not protrusive, the clypeal psammophore located at the midline of clypeus and in having the antennal scape of minor worker with many short, erect, bristly setae.

Minor worker description

Head. Head square; posterior margin of head planar or weakly convex; frons shining with indistinct microsculpture that is most pronounced on lower surfaces; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae concave; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Mandibular teeth in minor worker four to five; mandibles narrow, strap-like, internal and external margins parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four, or distinctly shorter than apical tooth and tooth no. two, tooth no. four vestigial, or distinctly shorter than apical tooth, but equivalent in length to remaining teeth, or absent; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron moderately shining and shagreenate throughout; anterior mesosoma in profile broadly convex; erect pronotal setae absent; in profile, metanotal groove a weak or vestigial furrow; propodeum shining and shagreenate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 1:1; erect propodeal setae present and abundant (greater than 12); appressed propodeal setulae long and closely aligned, creating pubescence; propodeal spiracle situated nearer to midpoint of propodeum than to its declivitous face, and shorter (length < than 0.50 × height of propodeum). Petiole. In profile, petiolar node cuboidal, rounded above; in full-face view, shape of petiolar node uniformly rounded; node shining and distinctly shagreenate-microreticulate. Gaster. Gaster shining with superficial microreticulation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour brownish-orange to dark russet.

Major worker description

Head. Head horizontally rectangular, broader than wide; posterior margin of head planar or weakly concave; cuticle of frons shining and smooth except for piliferous pits; frons consisting of appressed pubescence, with many short, unmodified, erect setae. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae distinctly concave; frontal lobes curved toward antennal insertion. Anterior clypeal margin broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Four to five mandibular teeth in major worker; mandibles narrow, strap-like, internal and external borders parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining with indistinct microsculpture that is most pronounced on lower surfaces; anterior mesosoma in profile steeply rounded anteriad, thereafter pronotum and whole of mesonotum flattened and on a higher plane than propodeum; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, indicated mainly by an angle and metathoracic spiracles; propodeum shining and generally smooth, with only weak indistinct shagreenation; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between 1:1 and 1:2; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae long and closely aligned, creating pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node tapered with blunt vertex; node shining and smooth with vestigial microreticulation anteriad. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting of thick, appressed setae that form pubescence, interspersed with numerous short, bristly, erect setae. General characters. Colour brownish-orange.

Measurements

Worker (n = 5): CI 104–127; EI 18–25; EL 0.25–0.31; HL 0.97–1.36; HW 1.00–1.74; ML 1.60–2.04; MTL 1.56–1.40; PpH 0.19–0.23; PpL 0.64–0.84; SI 72–136; SL 1.25–1.37.

Comments

This ant has the species-group level characters of the previous taxon, but differs from it in the form of the clypeus (not protrusive in this species) and its greater hairiness. Melophorus andersenioides has a wider distribution than the foregoing (being found in NSW, QLD and WA), and has been collected in red soil. Label notes on two pins associate it with nests of Iridomyrmex purpureus (as ‘I. detectus’, its junior synonym), and it is altogether possible that M. andersenioides is a social parasite on that species analogously with its relation.

Etymology

anderseni (see above) plus Greek -oides (‘resembling’).

Figure 27. 

Melophorus andersenioides sp. n.: major worker paratype (ANIC32-900082) frons (a), profile (b) and dorsum (c); minor worker holotype (ANIC32-900082–bottom ant) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus chrysus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker from Wungong Catchment 32°16'40"S, 116°08'12"E, Western Australia, 6-13 February 2009, D. Kabay, Water Corporation thinning: thinning plot dieback tree upland jarrah forest, 2A, 3Y [JDM32-004655] (WAM). Paratypes: Major worker and 2 minor workers from Streaky Bay, South Australia, 3 October 1957, B.B Lowery, mallee scrub, [folded paper label] ‘Melophorus, Streaky Bay: SA 450 m[iles] W of Adelaide, mallee scrub, sandy nest in [sic] among galleries of Melophorus laticeps Wh. 3.10.57 B.B. Lowery’ [ANIC32-900127] (ANIC); minor worker from Cambrai, South Australia, 1-4 February 1972, P.J.M. Greenslade, dune Ib (SAM); 2 minor workers from Mount Bruce 22°37'32"S, 118°17'05"E, September 1991, S van Leeuwen, Fire/Mulga Research 1-2a [JDM32-004804] (WAM).

Other material examined

South Australia: 16 mi N Gawler (Greaves, T.), Calca, near Streaky Bay (Lowery, B.B. [ANIC32-900146]). Victoria: 15 km WNW Yaapeet (Andersen, A.N.).

Diagnosis

Melophorus chrysis is a member of the M. anderseni species-group (maxillary palp segments short [not reaching neck sclerite], narrow and terminating in a subulate [awl-shaped segment]; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers [except chrysus], and four to six teeth in minor worker). This species is distinguished from others in the group by having, in profile, the petiolar node thickly squamiform in the minor worker, the major worker smooth and glossy in appearance, and also by having, in profile, the pronotum smoothly rounded and inclined at angle > 30°, and, in profile, the clypeus evenly convex or more strongly convex posteriorly, but not bulbous. The “pillipes” condition (whorls of fine, erect setae on appendages) occurs in some populations.

Minor worker description

Head. Head square; posterior margin of head weakly convex; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of short, erect and semi-erect setae interspersed with shorter decumbent setae and well-spaced, short, appressed setae. Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set at about midpoint of head capsule; in profile, eye set around midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes curved toward antennal insertion. Anteromedial clypeal margin broadly and evenly convex; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in minor worker; mandibles narrow, strap-like, internal and external margins parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum shining and smooth or with superficial and almost invisible microsculpture; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae variable in number, may be absent; appressed propodeal setulae sparse or absent, if present then not regularly spaced; propodeal spiracle situated on or beside declivitous face of propodeum, and longer (length ≥ 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster smooth and glossy; pilosity of first gastral tergite consisting of well-spaced, erect and semi-erect setae interspersed with regularly placed appressed setae, or consisting wholly or mainly of long, curved setae, appressed setae apparently absent. General characters. Colour light yellow to gamboge yellow.

Major worker description

Head. Head horizontally rectangular, broader than wide; posterior margin of head planar or weakly concave; cuticle of frons shining and smooth except for piliferous pits; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only. Eye moderate (eye length 0.20–0.49 length of head capsule); in full-face view, midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical. In full-face view, frontal carinae distinctly concave; frontal lobes curved toward antennal insertion. Anterior clypeal margin broadly convex with anteromedial dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles narrow, strap-like, internal and external borders parallel or nearly so; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining and mainly smooth, vestigial shagreenation most noticeable on humeri and mesopleuron; anterior mesosoma in profile broadly convex; erect pronotal setae short, (i.e., shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V- or U-shaped; propodeum shining and generally smooth, with only weak indistinct shagreenation; propodeum always smoothly rounded; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (at least a dozen); appressed propodeal setae sparse or absent, if present then not regularly spaced; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length less than 0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, shape of petiolar node tapered with blunt vertex; node shining and smooth with vestigial microreticulation anteriad. Gaster. Gaster weakly shining with indistinct shagreenation; pilosity of first gastral tergite consisting mainly of well-spaced short, semi-erect and decumbent setae. General characters. Colour gamboge yellow.

Measurements

Worker (n = 6): CI 101–117; EI 22–32; EL 0.18–0.25; HL 0.56–0.96; HW 0.57–1.12; ML 0.81–1.32; MTL 0.56–0.80; PpH 0.09–0.11; PpL 0.36–0.58; SI 76–116; SL 0.66–0.85.

Comments

This and the following species are rarely seen. This species is treated as a member of the anderseni group by Andersen (coming under ‘Group I’ in Andersen, 2007), and this is likely a correct placement. All four taxa possess short palps with an acuminate final segment, and the metatibial apical spur is absent. The close relationship of Melophorus chrysus to members of the M. fieldi complex is rendered more likely because it exhibits the ‘pillipes’ condition, otherwise seen only in ants belonging to that complex. The morphology is also similar. Melophorus chrysus is more common than the following taxon and has been collected in all Australian mainland states except NSW. Several ANIC specimens have been collected in mallee and this may be the usual habitat for the ant, but it has also been collected in marri forest just south of Perth, WA, and from a dune in SA. Most populations are glabrous, but several exhibit the very hairy ‘pillipes’ condition. No specimens have been sequenced and nothing is known of the ant’s habits apart from the information contained on the label mentioned for the ANIC paratypes.

Etymology

Chrysus (Greek) was the spirit of gold; noun in the nominative singular standing in apposition to the generic name.

Figure 28. 

Melophorus chrysus sp. n.: non–type major worker (ANIC32-900146–middle ant)frons (a), profile (b) and dorsum (c); minor worker holotype (JDM32-004655) frons (d), profile (e) and dorsum (f); distribution map for the species (g). Low resolution scale bars: 1 mm (b, c); 0.5 mm (a, d–f).

Melophorus subulipalpus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker from Tropicana Minesite 29°15'40"S, 124°35'50"E, Western Australia, January 2009, J. Summerhayes, pitfall tap, Casuarina, CA1:5 [JDM32-004701] (WAM). Paratypes: minor worker from Cambrai, South Australia, 24-28 February 1972, P.J.M. Greenslade, dune [ANIC32-900128] (ANIC); minor worker from 30 km ESE of Onslow 21°46'44"S, 115°22'01"E, Western Australia, 15 May 2006-29 August 2006, CALM Pilbara Survey, Site OYW12: ethylene glycol pitfalls [JDM32-004850] (WAM).

Other material examined

Western Australia: Packsaddle (van Leeuwen, S.)

Diagnosis

Melophorus subulipalpus is a member of the M. anderseni species-group (maxillary palp segments short [not reaching neck sclerite], narrow and terminating in a subulate [awl-shaped] segment; PF 6,4; metatibial apical spur absent; in full-face view, masticatory margin of mandible strongly oblique with four teeth in known major workers [except chrysus], and four to six teeth in minor worker). The major worker of this species is unknown. The minor worker of M. subulipalpus can be distinguished from its sister species (M. chrysus) by having, in profile, the pronotum more-or-less flattened and only very weakly inclined anteriad, the head and body weakly to moderately shining, the sculpture ranging from superficial microreticulation to evident shagreenation or minutely striate sculpture, and in having, in profile, the clypeus strongly convex, tending to bulbous. The “pillipes” condition has not been not seen in the few workers collected.

Minor worker description

Head. Head square; posterior margin of head strongly convex; frons shining and uniformly striolate, or matt or with weak sheen, microreticulate or microreticulate-shagreenate; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin straight, or broadly and evenly convex; clypeal psammophore set below midpoint of clypeus; palp formula 6,4. Five or six mandibular teeth in minor worker; mandibles narrow, strap-like, internal and external margins parallel or nearly so; in five-toothed workers third mandibular tooth distinctly shorter than apical tooth and tooth no. two, tooth no. four vestigial; masticatory margin of mandibles strongly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining, uniformly striolate or superficially microreticulate; anterior mesosoma in profile weakly elevated anteriad, thereafter gently sinuate, pronotum and mesonotum on same plane; erect pronotal setae absent; in profile, metanotal groove shallow, indicated mainly by an angle; propodeum shining and uniformly striolate, or matt or with a weak sheen and microreticulate; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity between1:1 and 1:2; erect propodeal setae always absent; appressed propodeal setulae long, each reaching setae behind and in front, but not forming pubescence; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiolar. In profile, petiolar node subcuboidal, vertex bluntly rounded; in full-face view, shape of petiolar node tapered with blunt vertex; node shining and distinctly shagreenate-microreticulate or superficially microreticulate. Gaster. Gaster weakly shining with indistinct shagreenation, or shining, shagreenate (‘LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour pale brownish-yellow to tan.

Measurements

Worker (n = 4): CI 102–108; EI 26–30; EL 0.22–0.25; HL 0.70–0.93; HW 0.72–0.93; ML 1.15–1.53; MTL 0.97–1.29; PpH 0.12–0.15; PpL 0.49–0.63; SI 135–140; SL 1.01–1.26.

Comments

Only four collections are known for this species, which can be distinguished from M. chrysus by its more matt appearance, less rounded pronotum and ochre colouration. The species occurs in WA and SA (at least). The sole South Australian specimen was collected from a dune, but otherwise nothing is known of the taxon.

Etymology

Latin subulus (‘awl’) plus palpus (‘stroking’/‘caress’; applied to the palps of an arthropod); noun in the nominative singular standing in apposition to the generic name.

Figure 29. 

Melophorus subulipalpus sp. n.: minor worker holotype (JDM32-004701) frons (a), profile (b) and dorsum (c); distribution map for the species (d). Low resolution scale bars: 0.5 mm (a–c).

Melophorus biroi species-group

This group of Melophorus is far and away the most diverse and species-rich in the genus. Many taxa are common but difficult to identify, even with expert analysis, because of the very similar appearance of anatomical structures and integument. The M. biroi species-group consists of five complexes (biroi, brevignathus, fieldi, oblongiceps, and wheeleri) representatives of all of which were successfully sequenced. The phylogenetic analysis of the complexes showed that each of the complexes were strongly supported, apart from M. oblongiceps which was missing the COI gene. As a consequence, the correct phylogenetic placement of M. oblongiceps is currently undetermined. The M. fieldi complex is the most derived within the group and this complex appears to be continuing to evolve rapidly, making the interpretation of molecular sequences just as difficult as interpretation of the morphology. Some continuing hybridization and lineage assortment is likely for M. turneri and several morphospecies that appear to be part of the M. turneri cluster. Most of the members of the broader species-group have a typical Melophorus habitus, with large-headed, short-limbed major workers and media and minor workers with normally proportioned heads and long limbs. In all probability most species are generalist scavengers of plant (mainly) and animal material, but the M. wheeleri complex appears to be granivorous. Belying the reputation of the genus, some species appear not to be thermophiles as they have been collected while active in cooler times of the year.

Melophorus biroi complex

Only seven out of eighteen members of this nominal complex of mostly small Melophorus have been genetically sequenced. A major surprise has been that several taxa initially placed in this complex (i.e., ludius, pusillus and translucens) due to their close morphological similarity were discovered to be only distantly related phylogenetically, and cannot be fitted easily even in the broader species-group. These have now been placed in a species-group of their own. Based on similarities of the propodeum, the flattened, plate-like node (in the major worker), and the depressed and slightly elongate head capsule, the following Melophorus species may prove to be in the clade that embraces M. biroi: biroi, castanopus, cuneatus, dicyrtos, latinotus, longiceps, macrops, microreticulatus, propebiroi and gracilis. This group, or, at least, the three members of the group that have been sequenced, appear to have a sister relationship to the M. mjobergi clade (which is decidedly hairier and has its own distinctive suite of apomorphies). Melophorus minimus appears to also belong to the M. biroi clade, but has not been sequenced. A second clade of Melophorus that shares a thick, porrect node in the minor caste, a rounded head and propodeum and a strongly microreticulate or distinctly scalloped mesopleuron includes the apparently rare Melophorus argus and M. turbineus.

Members of the mjobergi clade are small, compact Melophorus, which resemble M. biroi and are related to that taxon. Major workers of Melophorus graciliceps and M. lissotriches are not conspicuously different from biroi and its relatives apart from their hairiness, and are best separated from other members of the biroi complex on the basis of molecular data. Major and media workers of M. compactus, M. mjobergi and M. postlei, however, differ from those of M. biroi and its fellows by virtue of the deeply recessed area adjoining the lower frontal carinae and antennal insertions, the development of the torulus and, in M. mjobergi and M. postlei, by the appearance of the frontal carinae, which are vestigial. Major workers of these two species also have small pits around the head capsule. Minor workers of all members of the clade are not separated from those of the biroi clade by any one set of characters but are generally hairier and more obviously sculptured. This clade appears to have northern origins, and most collections have been taken north of the Tropic of Capricorn.

Melophorus argus Heterick, Castalanelli & Shattuck, sp. n.

Types

Holotype minor worker (top ant) from Kapalga, Alligator Rivers area, Northern Territory, 7-9 September 1983, P.J.M. Greenslade, 8 i traps, [ANIC32-066597] (ANIC). Paratypes: minor worker on same pin and with same details as holotype (ANIC); two minor workers from Kapalga, Alligator Rivers area, Northern Territory, 7-9 September 1983, P.J.M. Greenslade, 8 ii traps, (13), (MCZ).

Diagnosis

Melophorus argus can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is also placed in the M. biroi species-complex on the basis of a further suite of characters (viz, metatibia of major worker with only one preapical spur [except rarely in the mjobergi clade]; clypeal psammophore placed anteriorly at or just above anterior margin of clypeus in the minor worker and often in the major worker; head dorsoventrally compressed to varying degrees in the minor worker of most species with the eyes placed high on the sides; compact legs, and small body size [[(excluding mjobergi clade) HW of smallest minor 0.36 mm, average HW of smallest minors 0.46 mm; HW of largest known major 1.29 mm, average HW of largest majors (where known) 1.05 mm]). The minor worker of Melophorus argus (the major worker is unknown) can be recognised by a combination of a promently scalloped mesopleuron, a thickish, dorsall rounded petiolar node and a glabrous mesosoma that is bimodal when viewed in profile.

Minor worker description

Head. Head approximately oval with straight sides; posterior margin of head strongly convex; frons shining and smooth except for piliferous pits; frons consisting exclusively or almost exclusively of well-spaced, appressed setae only (small, erect setae, if present, usually confined to ocular triangle or posterior margin of head). Eye moderate (eye length 0.20–0.49 length of side of head capsule); in full-face view, eyes set at about midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes curved toward antennal insertion. Anteromedial clypeal margin broadly and evenly convex, or narrowly protrusive anteromedially, the protrusion with a square border; clypeal psammophore set at or just above anterior clypeal margin; palp formula 6,4. Five mandibular teeth in minor worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and teeth numbers two and four; masticatory margin of mandibles approximately vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron shining and smooth on dorsum, entire lower mesopleuron distinctly striolate-microreticulate; anterior mesosoma in profile pronotum smoothly rounded anteriad and flattened posteriad, mesonotum narrowly convex; erect pronotal setae absent; in profile, metanotal groove deep, ‘V’-shaped; propodeum shining, with multiple hair like striolae; propodeum angulate, propodeal angle blunt; length ratio of propodeal dorsum to its declivity about 1:1; erect propodeal setae always absent; appressed propodeal setulae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length < 0.50 × height of propodeum). Petiole. In profile, petiolar node broadly squamiform, almost a tubercle; in full-face view, shape of petiolar node uniformly rounded; node shining and smooth throughout. Gaster. Gaster smooth and glossy; pilosity of first gastral tergite consisting of well-spaced short, inconspicuous, appressed setae only, erect setae always absent. General characters. Colour concolorous brown.

Measurements

Worker (n = 2): CI 87–90; EI 29–32; EL 0.12–0.11; HL 0.42–0.43; HW 0.36–0.39; ML 0.54–0.58; MTL 0.26–0.27; PpH 0.07–0.08; PpL 0.21–0.21; SI 113–116; SL0.37–0.44.

Comments

This small, northern species is definitely known from the minor worker only, but the principal author of this paper has noted that a possible TERC major worker is similar to that of M. biroi. Only two pins, one of two workers from Kapalga, NT and one without any label data, were available for analysis. However, additional material for this species from the NT (Kakadu NP; Howard Springs; Wildman Riv.; Berry Springs; Brydle Hill) and also the Kimberley, WA (4 km W King Cascade) was briefly noted in the TERC Collection. Melophorus argus is recognizable by its completely glabrous appearance and its bimodal mesosomal profile. The Kakadu specimens were pitfall trapped by Greenslade, but nothing more is known of this ant.

Etymology

Latinized Greek argus (Greek argos ‘shining’); participle in the nominative singular.

Figure 30. 

Melophorus argus sp. n.: minor worker holotype (ANIC32-066597–top ant) frons (a), profile (b) and dorsum (c); distribution map for the species (d).

Melophorus biroi Forel

Melophorus biroi Forel 1907: 29 (combination in M. (Erimelophorus) by Wheeler 1935: 71). Type. Melophorus biroi Forel. Holotype (probable) major worker, Mt Victoria, Blue Mountains, New South Wales [HNHM] (examined: images of HNHM specimen provided by Zoltán Vas).

Melophorus marius Forel 1910: 66 (combination in M. (Erimelophorus) by Wheeler 1935: 71). Type. Holotype major worker Tennants [sic] Creek, Northern Territory [MHNG] (examined: MHNG specimen No. 235). Syn. n.

Melophorus fieldi propinqua Viehmeyer 1925: 36. Type. Syntype major worker, Liverpool, New South Wales [ZHMB] (examined: Automontage images © B.Schurian/ MfN-Berlin.de, of ZHMB specimen 5C8576). Syn. n.

Other material examined

Australian Capital Territory: Black Mt., Site 5 (Barnett, N.J. [ANIC32-029813]), Black Mt., Site 5 (Barnett, N.J. [ANIC32-029821]), Mt Ainslie (Lowery, B.B.), Yarralumla (Lowery, B.B.). New South Wales: 40 km NNW Louth, Lake Mere (Greenslade, P.J.M.), Armidale (Lowery, B.B.), Belanglo State Forest (Gush, T.), Bomaderry, Nowra (Lowery, B.B.), Cowan Creek (Lowery, B.B.), Fowlers Gap (Greenslade, P.J.M.), Kapunda, N Nyngan (Greenslade, P.J.M.), Lane Cove River, Burns Bay, Sydney (Lowery, B.B.), Mudgee (Lowery, B.B.), Myall Lakes (York, A.), Myall Lakes (Greenslade, P.J.M.), Myall Lakes (York, A.), Myall Lakes National Park (York, 0A.), Newholme Road, near Armidale (Sakurai, Y.), Pymble (Lowery, B.B.), Richmond (Greenslade, P.J.M.), St. Ives, Sydney (Lowery, B.B.). Northern Territory: 105 km N Yuendumu (Greenslade, P.J.M.), 25 km N Alice Springs (Shattuck, S.O.), about 3 km W Alice Springs (Feehan, J.E.), Tanami (Greenslade, P.J.M.), Tanami (Greenslade, P.J.M.), Tanami Desert (Greenslade, P.J.M.), vicinity of Ayers Rock (Allwood, A.). Queensland: ‘Gumbardo’ (Beutel, T.), ‘Merigol’ (Beutel, T.), 3.6 km NW homestead on Plum Pudding Track, Cravens Peak Station (Lemann, C. [ANIC32-036837]), 40 km E Cameron Corner (Greenslade, P.J.M.), 75 km E Cunnamulla (Greenslade, P.J.M.), Blair Athol Mine (Houston, W. [ANIC32-040331]), Proserpine, Thompson Creek (Raven & Burwell), Sandringham (Greenslade, P.J.M.), Sandringham (Greenslade, P.J.M.), St. George (Lowery, B.B.), Tindaree, Hannaford Rd South via Tara (House, A./Brown, S.), Wacol, Brisbane (Lowery, B.B.). South Australia: 10 km E Mt Ive Homestead (Greenslade, P.J.M.), 15 km NE Mt Bryan (Greenslade, P.J.M.), 50 km E Vokes Hill, Victoria Desert (Greenslade, P.J.M.), 53 km E Vokes Hill, Victoria Desert (Greenslade, P.J.M.), 5 km NW Ketchowla Homestead (Greenslade, P.J.M.), 5 km W Mt. Rough, Coorong-Keith (Greenslade, P.J.M.), 5 km WSW Pitlochry Homestead (Greenslade, P.J.M.), 6 km NW Mt Pleasant (Greenslade, P.J.M.), Belair (Greenslade, P.J.M.), Belair (Greenslade, P.J.M. [ANIC32-900109]), Belair (Greenslade, P.J.M.), Belair (Greenslade, P.J.M.), Belair (Greenslade, P.J.M.), Blyth (Lowery, B.B.), Brookfield Conservation Park (Shattuck, S.O.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Cambrai (Greenslade, P.J.M.), Chowilla (Greenslade, P.J.M.), Eyre Hwy, 9.7 km NE Cootra (Heterick, B.E. [M328]), Fairview Conservation Park, N Lucindale (Greenslade, P.J.M.), Gawler Ranges (Greenslade, P.J.M.), Glen Osmond (Greenslade, P.J.M.), Hale (Greenslade, P.J.M.), Katarapko Island (Loxton High [ANIC32-046389]), Koonamore (Greenslade, P.J.M.), Koonamore (Greenslade, P.J.M.), Koonamore, Milang Conservation Park (Greenslade, P.J.M.), Moorowie Plain (Greenslade, P.J.M.), Mt. Gunson (Case, T.J.), Mt. Remarkable, Flinders Ranges (Greenslade, P.J.M.), Napperby, Flinders Ranges (Greenslade, P.J.M.), North of Breakneck River, Kangaroo Island (Greenslade, P.J.M.), North Sandy Creek, Kangaroo Island (Greenslade, P.J.M.), Ocean Beach, Streaky Bay (Lowery, B.B.), Oraparinna, Flinders Ranges (Greenslade, P.J.M.), Para Wirra (Greenslade, P.J.M.), Rocky River, Kangaroo Island (Greenslade, P.J.M.), Salt Creek, Coorong (Greenslade, P.J.M.), Streaky Bay (Lowery, B.B.), vicinity of Nanam Well, Scorpion Springs Conservation Park (Museum Party), Victor Harbour (Greenslade, P.J.M.), Wudinna townsite (Heterick, B.E. [M331/M333]). Tasmania: Barnes Bay, N. Bruny Island (Lowery, B.B.), George Town (Littler, F.M.), Lefroy (Lowery, B.B.). Victoria: 15 km W Nyarrin (Greenslade, P.J.M.), 15 km WNW Yaapeet (Andersen, A.N.), 15 km WNW Yaapeet (Andersen, A.N.), Cape Schank (Lowery, B.B.), Cape Schank (Lowery, B.B.), Glenaladale National Park (Andersen, A.N.), Heathcote, near Bendigo (Lowery, B.B.), Hopetoun (Andersen, A.N.), Hurstbridge (Lowery, B.B.), Murray Sunset Natl. Park, Millewa South Bore Track, 5.2 km WSW Shearers Quarters (Lambkin, C., Yeates, D., Starwick, N. & Recsei, J. [ANIC32-043283]), Rotamah Island, Gippsland Lakes (Andersen, A.N.), Studley Park, Kew (Lowery, B.B.), Watsonia (Lowery, B.B.), Watsonia (Lowery, B.B.), Watsonia (Lowery, B.B.). Western Australia: 1 km W Canna (Heterick, B.E. [M317/M319]), 1.5 km S Koolyanobbing (Heterick, B.E. [M15]), 11 km W Terhan Water Hole (Heatwole, H.), 4 km W Ellendale Rd (Heterick, B.E. [M239/M240/M241/M242]), 4 km W Ellendale Rd (Heterick, B.E. [M243/M244/M245]), 46 mi WNW Norseman (Taylor, R.W.), 8 km NW Bluff Knoll, Stirling Ranges National Park (Ward, P.S.), Argyle Diamonds via Kununurra (Postle, A.T. [JDM32-001931]), Christmas Tree Well (Heterick, B.E. [M20]), Coomallo Downs (Heterick, B.E. [M12/M49]), County Downs Hsd (south boundary) (Heterick, B.E. [M248]), Eneabba-Leeman Rd. (Dunn, R. [JDM32-001943]), Ethel Creek (Varris, P.A. [JDM32-001940]), Eyre Hwy, 20 km N Norseman (Heterick, B.E. [M338]), Harrismith (Heterick, B.E. [JDM32-001927]), Hines Hill (Heterick, B.E. [JDM32-001929]), Hyden Cemetery (Heterick, B.E. [JDM32-001930]), Int. Holland Tr./Norseman Rd. (Heterick, B.E. [JDM32-001926]), Jurien (collector unknown [JDM32-001972]), Kojonup (Majer, J.D. [JDM32-001935]), Little Sandy Desert (Guthrie, N. A. [M144]), Mt Gibson rest area (Heterick, B.E. [M299/M300/M301]), Mulga, NE Goldfields (Pringle, H.J.R. [ANIC32-029570]), Ongerup-Jerramungup Rd. (Heterick, B.E. [JDM32-001925]), Sandstone Rd turnoff (B. .E Heterick [M296/M297/M298]), Sandstone Rd turnoff (Heterick, B.E. [M294]), Tammin (Clark, J.), The Granites’ Mt Magnet (Heterick, B.E. [M171]), Wannamal West (Heterick, B.E. [JDM32-001939]), Woolgangie (Heterick, B.E. [JDM32-001924]).

Diagnosis

Melophorus biroi can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is placed in the M. biroi species-complex on the basis of a further suite of characters (viz, metatibia of major worker with only one preapical spur [except rarely in the mjobergi clade]; clypeal psammophore placed anteriorly at or just above anterior margin of clypeus in the minor worker and often in the major worker; head dorsoventrally compressed to varying degrees in the minor worker of most species with the eyes placed high on the sides; compact legs, and small body size [[(excluding mjobergi clade) HW of smallest minor 0.36 mm, average HW of smallest minors 0.46 mm; HW of largest known major 1.29 mm, average HW of largest majors (where known) 1.05 mm]). Melophorus biroi is very similar to several other small or very small Melophorus. The minor worker can be distinguished from similar forms by its almost invariably glabrous mesosoma, the lack of erect setae, especially marginal setae, on the gaster, the weakly impressed metanotal groove, the truncate propodeum, the thin, widened petiolar node and the lack of heavy sculpture on the mesopleuron. Since the major worker of many M. biroicomplex species is not known, the M. biroi major worker cannot be diagnosed with high definition, and is best identified from nest series in which minor workers are also included. However, this subcaste has a weakly convex pronotum and mesonotum and a weakly ot moderately impressed metanotal groove enabling it to be separated from the very similar M. castanopus (flattened pronotum and mesonotum) and M. dicyrtos (strongly convex pronotum and mesonotum and deeply impressed metanotal groove), and the posterior clypeal margin is arched. The anterior clypeal margin often has a small dimple (as in many members of the M. fieldi complex). Melophorus biroi shows a lot of morphological variation, and there is substant