Twenty six new species of Leioproctus (Colletellus): Australian Neopasiphaeinae, all but one with two submarginal cells (Hymenoptera, Colletidae, Leioproctus)

Abstract Twenty six new species of Australian Leioproctus (subgenusColletellus) (Hymenoptera, Colletidae) are described: aberrans Leijs, sp. n., alatus Leijs, sp. n., albipilosus Leijs, sp. n., albiscopis Leijs, sp. n., aliceafontanus Leijs, sp. n., altispinosus Leijs, sp. n., aratus Leijs, sp. n., auricorneus Leijs, sp. n., bidentatus Leijs, sp. n., centralis Leijs, sp. n., ciliatus Leijs, sp. n., claviger Leijs, sp. n., consobrinus Leijs, sp. n., constrictus Leijs, sp. n., laciniosus Leijs, sp. n., longivultu Leijs, sp. n., lucidus Leijs, sp. n., nitidifuscus Leijs, sp. n., pectinatus Leijs, sp. n., pilotapilus Leijs, sp. n., quadripinnatus Leijs, sp. n., rubicundus Leijs, sp. n., rubricinctus Leijs, sp. n., similis Leijs, sp. n., splendens Leijs, sp. n., submetallicus Leijs, sp. n. High resolution images of diagnostic characters for all type specimens are included. Identification keys are provided.


Introduction
The monotypic subgenus Leioproctus (Colletellus) was established by Michener (1965) for L. velutinellus, an unusual species of Australian neopasiphaeine bee with two submarginal cells and ciliate, rather than pectinate, inner hind tibial spurs. Formerly Leioproctus was classified under the Colletinae (Michener 2007), but recent phylogenetic analyses of the world's Colletidae indicated its position under Neopasiphaeinae (Almeida et al. 2011). Now, more than 50 years later, examination of numerous specimens collected by T.F. Houston (WA-Museum) and others, as well as specimens collected on a number of Bush Blitz surveys in remote locations of Australia indicates that L. (Colletellus), is a rather speciose group of bees. The latter surveys are the result of a partnership between the Australian Government, BHP Billiton and Earthwatch Australia to document fauna and flora from selected national reserves. These surveys regularly result in the discovery of new invertebrate species (e.g., true bugs: Symonds and Cassis 2014;spiders: Baehr et al. 2013;bees: Hogendoorn et al. 2015, Leijs andHogendoorn 2016; review of new described species: Taylor et al. 2017a, b).
Below, we describe 26 new species. Morphologically, the bees treated here key out to L. (Colletellus) when using Michener's (2007) identification key to the subgenera of Leioproctus of the Australian Region, with the exception of a single character: not all females have a ciliate hind tibial spur. Removing the latter character, the distinctive characters for the subgenus are a combination of two submarginal cells, convex clypeus and supra clypeal area, a large, parallel-sided stigma and the jugal lobe of the hind wing long, i.e. extending well below the level of cu-v.

Materials and methods
For descriptions of the new species the terminology used by Michener (2007) was followed. A Leica stereomicroscope with auto-montage imaging stacking software was used to obtain high-resolution images of all species. A compound microscope (Nikon, Eclipse 50i) and Zerene Stacker was used to image male genitalia and metasomal sterna seven and eight. Head measurements were taken from high-resolution frontal head images using the Leica auto-montage software. All measurements were converted relative to the head width, which was set to 50 units (following Houston 1990).
Abbreviations for these relative measurements are as follows: AOD antennocular distance; ASD antennal socket diameter; HL head length; HW head width; IAD interantennal distance; LFW lower face width, measured between lowest eye margins; OOD ocellocular distance; OAD ocellantennal distance; UFW upper face width, measured between upper eye margins; OW width of ocellar cluster.
Abbreviations for wing measurements are: MSR ratio of stigma length and marginal cell length measured on wing costa; FSR ratio of the lengths of the first submarginal cell and second submarginal cell; SFR ratio of the lengths of the stigma and first submarginal cell.
The terminology for integument sculpture, grades of pit and pubescence density and pit size follows Houston (1975; Fig. 1). Integument sculpture was observed using 40× magnification and YK-B144T LED ring elimination.
Some of the specimens treated here were also submitted to BOLD (Barcode of Life Database) for DNA barcoding using the cytochrome c oxidase subunit 1 gene. Specimen details, including DNA sequence, collecting dates and locality information can be accessed in BOLD under the project Australian Bee Survey, e.g., http://www.boldsystems.org/index.php/Public_RecordView?processid=AUSBS145-12. AUSBS-numbers are presented under material examined. Repositories:

AM
Australian Museum, Sydney ANIC Australian National Insect Collection, Canberra SAMA South Australian Museum, Adelaide QM Queensland Museum, Brisbane WAM Western Australian Museum, Perth

Results and discussion
Twenty-six new species of Leioproctus are described. All specimens of these species key out to subgenus Colletellus when using Michener's (2007: 148) identification key to the subgenera of Leioproctus of the Australian region. The type species of L. (Colletellus), L. velutinellus Michener, 1965 was unique amongst Leioproctus species due to its possession of a combination of two, rather than three, submarginal cells, convex clypeal and supraclypeal area, large parallel-sided stigma, long jugal lobe of the hind wing and ciliate rather than pectinate inner hind tibial spurs and long and pointed basitibial plates in females. The 26 additional species described here all conform to these characters with the exception of the hind tibial spurs in females and the shape of the basitibial plates. While 10 of the newly described species have ciliate spurs, 9 have pectinate spurs, and  Houston (1975), with permission from CSIRO Publishing.
16 of the additional species have short and rounded basitibial plates. Morphological characters as well as molecular data indicate that these species are almost certainly not a monophyletic group, but multivariate analyses of a large number of body size measurements as well as characters with discrete states did not result in clear clusters of species.
Although it may be possible to separate species groups based on wing venation, we hesitate to do so without the inclusion of independent molecular data for the majority of the species. Until now fresh tissue is only available from four of the L. (Colletellus) species, mainly from specimens collected at Bush Blitz surveys, and these have been DNA barcoded. Neighbour joining analyses using PAUP* (Swofford 2001) based on the DNA sequence data available from BOLD that include 22 other Australian Leioproctus species showed two independent groups of L. (Colletellus) species amongst other Leioproctus. Although this analysis is preliminary and only based on four L. (Colletellus) species it supports the idea that L. (Colletellus) as it stands now is paraphyletic. One of the groups, consisting of three South Australian species (L. aberrans, L. laciniosus and L. rubicundus) have pectinate inner hind tibial spurs in females and have a wing venation that differs from all other species described here. If corroborated, this would also indicate that a reduction of the number of submarginal cells has happened multiple times independently within Leioproctus.

Wing vein reduction
Wing vein reduction is a common phenomenon with reduction in body size in Hymenoptera (Danforth 1989). In L. (Colletellus) this seems to have occurred in two different ways. In the majority of the Leioproctus species with three submarginal cells, the first recurrent vein is distal to the first submarginal cross vein, as is also the case for most L. (Colletellus) species. It therefore seems that the majority of the L. (Colletellus) species lost the second submarginal cross vein (e.g., L. centralis: Fig. 2D). This is also demonstrated in species where the second submarginal cross vein is rudimentary (e.g., L. auricorneus: Fig. 2E). However, in the South Australian species L. rubicundus and L. laciniosus the first recurrent vein is basal to or meeting the submarginal cross vein ( Fig. 2A, B), suggesting that in these species the first submarginal cross vein was lost. Regaining lost veins may be possible when considering the venation of L. aberrans (Fig. 2C), a species that has three submarginal cells and which is phylogenetically very close to L. rubicundus and L. laciniosus, uncorrected pairwise sequence divergence 6.0-8.3% (sequences available in BOLD). The same explanations are possible for other Leioproctus subgenera with two submarginal cells. In L. (Andrenopsis) and L. (Euryglossidia) the position of the first recurrent vein is distal to the first submarginal cross vein and it is therefore likely that these taxa lost the second submarginal cross vein, while L. (Baeocolletes) and L. (Filiglosssa) have possibly lost the first submarginal cross vein, because the position of the recurrent vein is basal or meeting the submarginal cross vein. Examination of Almeida's Colletidae phylogeny suggest independent losses of submarginal cross veins for each of these above mentioned Leiproctus subgenera (Almeida et al. 2011).

Distribution and phenology
Leioproctus (Colletellus) are widespread in arid and semi-arid environments of Western Australia, Northern Territory and South Australia west of approximately 138 degrees longitude (Fig. 3). The majority of the specimens were collected during the months August, September and October (Table 1), with a significant negative correlation between latitude and collection date (r 2 = 0.4044; p < 0.001), Fig. 4), indicating a response in activity to temperature. The two outliers represent species L. albipilosus collected north of Broome in April, WA and a single male of L. claviger collected at Dawesville, WA in May. These records are at odds with most other records of these species, which show collecting dates between the end of July and late October.

Flower visitation
Leioproctus ( Those species that have a multitude of flower records visited a multitude of plant families and genera, indicating that they are generalist flower visitors. However, lecty is often classified according to the number of plant genera and families from which   pollen is collected (Cane and Sipes 2006) -information that is usually not recorded on the specimen labels. Therefore, we conclude that, currently, there is no evidence that L. (Colletellus) species are oligolectic.

Revised identification key to the subgenera of Leioproctus for species with two submarginal cells (modified from Michener 2007)
N.B. Specimens of L. aberrans have three submarginal cells. While this species keys out to Leioproctus s. str. when using Maynard's (2013) key to the subgenera of Leioproctus with three submarginal cells, it does not meet the other diagnostic characters for Leioproctus s. str., because the female facial fovea is absent, the antennal scape does not reach the median ocellus, apical hair bands are present on T2-4, and the male flagellum is short. Hence, the species is included here.  Michener (1965), based on the type species L. velutinellus is no longer accurate with the addition of numerous species to this subgenus. Body length of 5-6.7 mm; eyes converging below; clypeus not protuberant; facial fovea absent; scape short, not approaching level of anterior ocellus, antenna as a whole short, median segments of flagellum much broader than long, with the exception of L. aratus which has an elongated flagellum with median segments longer than wide; two submarginal cells, however some species show incomplete or complete additional submarginal cross veins; stigma large, not parallel sided, more than half of length of costal edge of marginal cell; jugal lobe exceeding cu-v; metanotum not tuberculate; propodeum in profile with subhorizontal surface, curving onto vertical surface without sharp differentiation; inner hind tibial spur ciliate or pectinate; basitibial plate elongated and pointy or short and rounded; scopa plumose; claws cleft; metasoma in most species without distinct hair bands, but occasionally faint apical hair bands laterally, with the exception of L. aberrans and L. laciniosus which have distinct apical hair bands on T2-4; post gradular areas often depressed, especially in males, with orange-brown integumental colouring; large variation in the shape of male S7, especially with regard to the shape , the number of lateral lobes and the placement of setae.
The species in this subgenus are not difficult to identify because there are clear differences among species in integumental structure, especially on the clypeus, frons, scutum, metapostnotum and metasoma, as well as remarkable diversity of shapes of the male S7.

Identification keys
The following keys are based on our current knowledge of the species. Considering the low numbers of specimens and localities of several species, as well as the fact that for a number of species only a single sex is known, one should be aware, when using the keys, of the high likelihood of encountering undescribed sexes of species or even new species not treated in this paper.

Identification key to the females of Leioproctus (Colletellus) (20)
The number in brackets shows the number of species relevant to the character choices in each couplet. Structure: terga not depressed anteriorly; BTP rounded; BTP/tibial length ratio 0.2; inner hind tibial spur pectinate with 8 strong teeth.
Flower records. Allocasuarina campestris (Casuarinaceae). Distribution. Figure 8F. Etymology. The specific epithet refers to the white scopa pubescence on the hind tibia of the female.  Figure 9I. Etymology. The specific epithet refers to the distribution of this species around Alice Springs.  Distribution. Figure 10I. Etymology. The specific epithet refers to the robust setae on the tip of the ventral apical lobe of male sterna 7. It also is a translation of the name of our linguistic advisor Wiebe Hogendoorn.  Flower records. Prasophyllum fimbria (Orchidaceae). Distribution. Figure 11I. Etymology. The specific epithet refers to very coarse pit-reticulate sculpture on the head.      Distribution. Figure 13J. Etymology. The specific epithet refers to the two teeth on the ventral margin of the clypeus. Sculpture: scutum smooth, closely punctate; metapostnotum dullish, fine transverse reticulate; T1 lineo-reticulate, T2-3 transverse lineo-reticulate; clypeus smooth, openly to closely punctate; supraclypeal area smooth, openly to closely punctate; labrum dull, brown-orange; ocellocular area smooth without punctures; frons smooth closely punctate; scape brown, smooth and sparsely punctate ventrally.
Coloration: terga anteriorly brown, posterior margins transparent orange; labrum black; mandibles brown with red-brown tip; flagellum brown, lighter towards the tip; scape black.
Pubescence: scutum: medium to short, sparse brown; scutellum: medium to short, sparse brown; sterna S5 with fringe of dense white hairs.
Flower records. No data. Distribution. Figure 21F. Etymology. The specific epithet refers to the smooth and shiny integument on head, scutum and terga of this species. Paratypes 5 females, same locality data as holotype, AM, K447300-03, 05. Diagnosis. Entire body smooth and shiny, abdomen brown, terga with transparent posterior margins.
Flower records. No data. Distribution. Figure 22F. Etymology. The specific epithet refers to very smooth and brown integument of large parts of the body of this species. Diagnosis. Ocellocular area openly punctate, propodeal triangle small, shiny and micro alveolate, inner hind tibial spur strongly pectinate.
Coloration: terga anteriorly black, posterior margins transparent orange, fovea on T2 black; scopa white; mandibles orange brown with darker tip; scape with white pubescence F1-9 black, orange towards the tip.
Flower records. No data. Distribution. Figure 25I. Etymology. The specific epithet refers to thin feathery like apical lobes of the male sterna 7.   S7: dorsal apical lobe absent, ventral apical lobe large, branched setae present on apico-medial area of ventral apical lobe.
Flower records. Borya sp. (Boryaceae). Distribution. Figure 28F. Etymology. The specific epithet refers to the common habitus of this species within this subgenus. Paratype female, same locality data as holotype, WAM 21485. Diagnosis. Integument of metapostnotum and terga smooth and shiny without punctures, ocellocular area smooth, closely punctured.
Pubescence: scutum: short, close, brown; scutellum: short, close, brown. Flower records. Calandrinia sp. (Montiaceae). Distribution. Figure 29F. Etymology. The specific epithet refers to the smooth and shiny integument on metapostnotum and terga of this species. Diagnosis. The only species with faint metallic integument of head and thorax.
Coloration terga anteriorly black, posterior margins almost not transparent, brown; mandibles black with brown tip.
Flower records. Grevillea sp. (Proteaceae). Distribution. Figure 30F. Etymology. The specific epithet refers to the faint metallic shine on the head and thorax.