Systematics of Australian Thrasorinae (Hymenoptera, Cynipoidea, Figitidae) with descriptions of Mikeiinae, new subfamily, two new genera, and three new species

Abstract The Australian Thrasorinae are revised and Mikeius is transferred to Mikeiinae Paretas-Martínez & Pujade-Villar, subfam. n., and Mikeius clavatus Pujade-Villar & Restrepo-Ortiz, sp. n., is described. Two new genera of Thrasorinae are erected: Cicatrix Paretas-Martínez, gen. n., including Cicatrix pilosiscutum(Girault), comb. n. from Amblynotus, Cicatrix schauffi (Buffington), comb. n. from Mikeius, and Cicatrix neumannoides Paretas-Martínez & Restrepo-Ortiz, sp. n.; and Palmiriella Pujade-Villar & Paretas-Martínez, gen. n., including Palmiriella neumanni (Buffington), comb. n. from Mikeius, Thrasorus rieki Paretas-Martínez & Pujade-Villar, sp. n., is also described. A phylogenetic analysis of 176 morphological and biological characters, including all these new taxa and all genera previously included in Thrasorinae, was conducted. All subfamilies were recovered as monophyletic, with the following relationships: Parnipinae (Euceroptrinae (Mikeiinae (Plectocynipinae (Thrasorinae)))). A worldwide key to the subfamilies of Figitidae is provided that includes the new subfamily, as well as a key to genera Thrasorinae.

Thrasorinae is a stem group of figitids (Buffington et al. 2007) associated with galls of other wasps (Cynipoidea and Chalcidoidea) on various trees and bushes. They are parasitoids of the gall inducers or other hymenopteran inhabitants in the galls with which they are associated (Ronquist 1999;Buffington and Liljeblad 2008). Hence, the group is important for elucidating the evolutionary history of Figitidae, in particular, and the Cynipoidea as a whole, with its different life strategies of entomophagy and phytophagy. Prior to this study, Thrasorinae included the four genera Thrasorus Weld (two species: Australia), Mikeius Buffington (six species: Australia), Myrtopsen Rübsaamen (eleven species: two Holarctic and nine Nearctic), and Scutimica Ros-Farré (two species: Neotropical). Thrasorinae are characterized by the circumtorular impression ( Fig. 2A, D, 3A), not present in any other figitids (Pujade et al. 2008;Ros-Farre and Pujade-Villar 2007;Ros-Farre and Pujade-Villar 2009;present study).
Following the examination of many undetermined specimens of Thrasorinae in the Australian National Insect Collection (ANIC) and the Queensland Museum (QM), as well as the type material of all species included in Mikeius Buffington, new questions arose regarding the taxonomy of Thrasorinae. First, an undescribed species of Mikeius was discovered (described herein); second, two species originally described in Mikeius were determined to render the genus polyphyletic, and new generic assignments are required; and third, phylogenetic analyses determined that the inclusion of Mikeius within Thrasorinae renders the subfamily paraphyletic with respect to Plectocynipinae. In response to these discoveries, Mikeiinae is described as a new subfamily to accommodate Mikeius, and species previously described in Mikeius are moved into other genera. In two cases, no current genus concept could accommodate these species, and the two new genera Cicatrix, gen. n., and Palmiriella, gen. n., are herein described. The goal of this study is to bring clarity to the taxonomic and phylogenetic relationships of these unusual groups of figitid wasps.
Specimen illustration and observation. Environmental scanning electron micrographs (ESEM) were obtained at Barcelona University with the FEI Quanta 200 ESEM without any coating at 15 KV. Additional ESEM images were obtained either with a Hitachi TM3000 E-SEM, or an Amray 1810 SEM under a vacuum, using a lanthanum hexaboride electron source (LaB6) at 10 Kv, both housed at the National Museum of Natural History, Smithsonian Institution. Images were edited using Adobe CS4 Software (Adobe, Inc). The terminology for morphological structures comes from Richards (1977), Ronquist and Nordlander (1989), Ronquist (1995), Ros-Farré et al. (2000), and Ros-Farré and Pujade-Villar (2007), and the sculpture terminology follows Harris (1979). Measurements and abbreviations in the descriptions include: F1-F12, first and following flagellomeres; T3-T4, third and fourth abdominal tergites; antennal formula is given with the length:width ratio of each segment.
Phylogenetic analysis. Twenty-two taxa were included in the phylogenetic analysis (Table 1), representing all genera previously and currently included in Thrasorinae, and all new taxa and combinations described in this work. Three species of each genus were included (except for monotypic genera or those with less than three species), so as to capture the morphological diversity of each genus. Parnips nigripes (Barbotin, 1964) was chosen as an out-group based on Buffington et al. (2007). The analysis was based on a morphological dataset of 172 morphological and 4 biological characters modified from Buffington et al. (2007); the character list can be found in Appendix 1. These characters represent the variability in the external morphological diversity of all the species studied, excluding those characters present in only one species; characters utilized in previous phylogenetic studies are indicated. Due to their rarity, some species were not dissected and examined internally; characters requiring dissection for coding were left as '?'. The resulting data matrix (Appendix 2), which included 79 parsimony-informative characters, was analyzed using PAUP* (Swofford, 2002) employeing 10,000 multiple random addition sequences, followed by TBR swapping with branches of maximum length zero collapsed and steepest descent set to 'off'. For bootstrap analyses (Felsenstein 1985), we employed a simple addition sequence with Parnips nigripes as the reference taxon, followed by 1000 bootstrap replicates, each replicate employing 100 TBR swapping replications.
Coloration. Head and mesosoma dark brown to black, antenna and legs yellowish to brown. Metasoma light brown to black.
Forewing. Short setae present on wing surface and along margins. Radial cell closed along anterior margin, 2 to 2.5 times longer than wide, R2 almost straight; areolet absent.
Legs. Metatibia with two spurs, sub-equal in length, not exceeding one-third the length of tarsomere 1.
Metasoma. Base of T3 with a complete or incomplete ring of setae. Tergite 3 smaller than T4; T4 large, covering almost entire metasomal surface; remaining terga short, telescoped within T4; entire metasoma shiny and smooth.
Comments. In the original description of Mikeius, Buffington (2008) erroneously described species of the genus as having 12 flagellomeres in the female antenna; the correct number is 10 or 11 ( Fig. 1 D and E).
Biology. Associated with Chalcidoidea (Hymenoptera: Apocrita) that induce galls on species of Acacia (Fabaceae) and Eucalyptus (Myrtaceae), although most of these host records await verification through isolated rearing (Buffington, 2008 Table 2); further distinguished from Euceroptrinae by the absence of an areolet in the forewing and the absence of a lateral pronotal carina. Additional characters that distinguish Thrasorinae from other Figitidae can be found in the key to subfamilies below.
Comments. In the redescription of Thrasorus, Buffington (2008) erroneously described species of the genus as having 12 flagellomeres in the female antenna; the correct number is 11.
Coloration. The entire body with the same coloration, light brown or chestnut depending on the specimen. Head ( Fig. 2A, D). Face and frons with abundant setae . Face with transverse carinae, strong across entire face, or only marked at lateral sides of face, smoother, tending towards strigae. Clypeus distinctly projected anteriorly, curved ventrally, clypeopleurostomal lines well developed. Malar furrow coriaceous. Occiput and genae smooth without carinae. Circumtorular impression present.
Forewing. Short setae present on wing surface and along margins. Radial cell closed along anterior margin, two times longer than wide, R2 almost straight; areolet absent.
Legs. Metatibia with two spurs, sub-equal in length, not exceeding one-half length of tarsomere 1.
Biology. Unknown. Distribution. Australia. Etymology. From the Latin word cicatrix, meaning "scar", refering to the carinae that resemble a scar through the face. Gender is masculine.
Taxonomic comments. Girault (1929) described Amblynotus pilosiscutum, and Weld (1952) transferred the species to Melanips. This species has the circumtorular impression and thus belongs to Thrasorinae. However, the results of the phylogenetic analysis and the diagnostic characters summarized above indicate that this species cannot be accommodated by any currently recognized genus, thus we describe Cicatrix, gen. n., to contain C. pilosiscutum (Girault) as well as C. neumannoides, sp. n., and C. schauffi (Buffington), comb. n.
Redescription. As in generic description (see above) with the following specific characters: Length. Diagnosis. Similar to C. neumannoides, sp. n., in having female antenna with 10 flagellomeres (Fig. 2F) and a face horizontally striate only on the lateral areas (Fig. 2D) (C. pilosiscutum, comb. n., has female antenna with 11 flagellomeres and much stronger carinae crossing the entire face), but differs from C. neumannoides sp. n. by having a long median mesoscutal impression and subtriangular scutellar foveae (Fig. 2B).
Redescription. As in generic description (see above) with the following specific characters: Length. Female: 3.9 mm. Male unknown.
Description. As in generic description (see above) with the following specific characters. Mesosoma. (Fig. 2E) Median mesoscutal impression short, only indicated basally, not reaching one-fifth length of scutum. Scutellar foveae rounded.
Etymology. The specific name neumannoides means "related to neumanni", referring to the fact that the specimens used to describe this species were previously included in the type series of M. neumanni. Biology. Unknown; label data suggests an association with Acacia. Distribution. New South Wales and Western Australia, Australia. Taxonomic comments. Although Buffington (2008) recognized two specimens of Mikeius neumanni in the collection at ANIC, he used only one specimen in his description of the taxon, designating it as the holotype. The species neumanni (based on the holotype) is transferred to Palmiriella, gen. n., below, and the second specimen, in addition to another specimen discovered in ANIC, belongs to Cicatrix.
Description. See description, biology and distribution of type species below. Etymology. The new genus is dedicated to our colleague and good friend Palmira Ros-Farré, who has helped us for many years with our little wasps. Gender is feminine.
Taxonomic comments. The holotype of Mikeius neumanni Buffington, unlike the other species included in Mikeius, does have the circumtorular impression diagnostic for Thrasorinae. For this reason, this species is transferred from Mikeius to the new thrasorine genus Palmiriella. Characters summarized in the diagnosis below and phylogeny in Fig. 5 justify the erection of the new genus. Coloration. Head and mesosoma black, antennae yellowish except scape, brown, metasoma medium brown. Legs light yellow except tibia and metatarsi, brown.
Forewing. Short setae present on wing surface and along margins. Radial cell closed, 2.3 times longer than wide; R2 almost straight, basal vein distally widening; areolet absent.
Legs. Metatibia with two spurs, sub-equal in length, not exceeding one-half length of tarsomere 1.
Metasoma (Fig. 3F). Petiole very short, almost not visible. T3 and T4 fused into a syntergum, not covering the entire metasomal surface; remaining terga short, telescoped within T4; entire metasoma shiny and smooth. Hypopygium and ventral spine visible. Base of syntergum with only some scattered setae. Diagnosis. Differs from other species of Thrasorus by having small scutellar foveae not clearly defined in posterior margin (Fig. 4B); other species of Thrasorus have scutellar foveae clearly delimited in the entire circumference (Fig. 4D). Further differs from other Thrasorus species by having a well-defined median mesoscutal impression (arrow, Fig. 4B); in other Thrasorus, the impression is not present, or at most, a very small incision can be seen (Fig. 4D). Description. Length. Female: 3.0-3.2 mm; males: 3.2-3.3 mm. Coloration. Head and mesosoma black, antennae brown, and metasoma pale brown. Legs pale yellow except coxae, brown.
Forewing. Short setae present on wing surface and along margins. Radial cell closed, 1.9 times longer than wide; R2 almost straight; areolet absent.
Legs. Metatibia with two spurs, sub-equal in length, not exceeding one-half length of tarsomere 1.
Biology. Unknown host on Acacia galls (based on label data). Distribution. Australia, Queensland. Etymology. Named after E.F. Riek, who worked before us on Australian Cynipoidea.
Taxonomic comments. In the QM, there is one specimen labelled as 'Amblynotus berlesei' by Girault. In ANIC, there are six specimens on one large card with a determination label placed by Riek, stating that taxon is 'T. berlesei (Grlt)'. But as Buffington (2008) pointed out, this species was never published by Girault nor Riek. As this name is a nomen nudum after Buffington (2008), we described it as a new species. In ANIC, there is another large card that has six specimens of T. rieki, sp. n., mixed with Chalcidoidea specimens.

Discussion
Ros-Farré and Pujade-Villar (2007)  Though the shape of this impression is variable among genera and species of Thrasorinae, the presence of this character is constant in all the species of the subfamily and thus must be considered as a strong synapomorphy of the Thrasorinae. The circumtorular impression in Scutimica is more laterally directed and wide, with a few 'ribs' inside (Fig. 9A); in Myrtopsen the impression can vary from very tight and deep in some species (Fig. 9B) to a state similar to that in Scutimica; in Palmiriella ( Fig.  3A) and Thrasorus (Fig. 4A), the impression is well defined, deep, wide, and delimited by a small crest; in Cicatrix, the impression is also wide but not delimited by a crest, and it is deeper in some species ( Fig. 2A) than in other (Fig. 2D). Three genera previously included in Thrasorinae that do not possess this character have recently been moved to new subfamilies: Plectocynips and Pegascynips to the Plectocynipinae (Ros-Farré and Pujade-Villar 2007), and Euceroptres to the Euceroptrinae (Buffington and Liljeblad 2008).
Mikeius, described by Buffington (2008), was included in the Thrasorinae based on its general morphology and its association with chalcidoid galls. However, as shown here, Mikeius does not have the circumtorular impression (Fig. 1A), diagnostic of Thrasorinae. Further, Mikeius possesses a character not present in the other subfamilies treated here: projected pronotal plate lacking, the area instead being marked by two carinae in the median part of the pronotum that do not reach the anterior margin of the mesoscutum (Fig. 1G). A similar state can be found in Euceroptres (Buffington and Liljeblad 2008) and Lonchidia (Fig. 8E). In both Mikeius and Euceroptres, the submedial pronotal depressions of the plate (lateral fovea of pronotum, Buffington 2009) are present and are open laterally. Overall, the impression of the observer is that the pronotal plate is lacking entirely; we argue here that the plate is present, evidenced by the presence of the submedial pronotal depressions, as well as the anterior part of the pronotal plate (portion of plate ventral to submedial pronotal depressions). The portion of the plate that is reduced is the posterior part of the pronotal plate, or the portion of the plate dorsal to the submedial pronotal depressions. The arrow in Fig. 1F shows where the lateral portion of the dorsal part of the pronotal plate fades into the remaining cuticle, just ventrad of the anterior margin of the mesoscutum. Further, the dorsal margin of the plate is completely undefined, as compared with the state found in Palmiriella (Fig. 3E) and Thrasorus (Fig.  4B). Unfortunately, to fully appreciate this character, the head must be removed from a specimen in hand.
The morphology of the metasoma is a very important character and is frequently used in all Figitidae subfamilies to separate different genera. Within Thrasorinae, there are two main metasomal morphologies: T3-T4 free (Thrasorus, Cicatrix), and T3-T4 fused into a syntergum (Palmiriella, Scutimica, Myrtopsen). The primary difference between Thrasorus and Cicatrix is the sculpturing of the mesoscutum. Though the sculpturing on the mesoscutum can be variable in other groups of Figitidae, in the 'pool' of genera treated in this paper, mesoscutal sculpture is useful and unique character. Thrasorus is the only genus, not only among Thrasorinae but also among all the genera previously included in this subfamily (Plectocynips, Pegascynips, Euceroptres, Mikeius), that aside from notauli, lacks sculpturing of any kind (microsculpture, carinae or parapsides) in the mesoscutum; we believe that this character is enough to justify the separation of Thrasorus from Cicatrix and the other thrasorines.
The characters that differentiate Palmiriella from Scutimica and Myrtopsen are detailed in the diagnosis of the genus (see above). The combination of the smooth face (Palmiriella being the only genus among Thrasorinae and genera previously included in the subfamily lacking any kind of sculpture on face), shape of syntergum T3-T4, shape of scutellum, shape of pronotum, and absence of sculpturing on pronotum, distinguish Palmiriella from Scutimica and Myrtopsen. The differences between Scutimica and Myrtopsen have already been remarked and discussed in Ros-Farré and Pujade-Villar (2007).
The results of the phylogenetic analysis are summarized in Fig. 5. Two trees of length 190 were recovered, with a CI of 0.58, RI of 0.73, and RC of 0.43. All subfamilies treated here were recovered as monophyletic, with following pattern of relationship: Parnipinae (Euceroptrinae (Mikeiinae (Plectocynipinae (Thrasorinae)))). It is clear that Mikeius renders the Thrasorinae paraphyletic, supporting the description of Mikeiinae, and that Cicatrix and Palmiriella are distinct clades. Erecting a new subfamily for a single genus is not desirable, but the only alternative to this while respecting the clades recovered in the phylogenetic analysis would be grouping together Mikeius, Palmiriella, Thrasorus, Cicatrix, Scutimica, Myrtopsen, Plectocynips and Pegascynips in a single subfamily; we feel this grouping is undesirable from the standpoint of predictability, since these genera contain species possessing markedly different biological and morphological attributes, and still would lack a single common diagnostic character for all of them. As currently defined, each of the subfamilies recognized here has its own diagnostic character: long metatibial spur for Plectocynipinae, circumtorular impression for Thrasorinae and two carinae in median area of pronotum not forming a projected pronotal plate for Mikeiinae.
The Thrasorinae from Australia are one of the most poorly known groups of figitids. More field data and specimens would help to clarify the status of this group and some taxa described here. However, there is no single researcher in Australia dedicated to the study of Cynipoidea, and workers on Figitidae wanting to study the systematics of this group must rely on 'rare' specimens coming from non-target collections while pursuing the sampling of other groups. The study we present here has been done with all the thrasorines and Mikeius that have been collected, curated, and deposited in museums worldwide.  Mesoscutum with horizontal microsculpture (Fig. 2B, E); face with strong or weak transverse strigae ( Fig. 2A, D)  Mesoscutum smooth, at most with some piliferous punctures (Fig. 4B, D); face without transverse strigae; if present, strigae are weak (Fig. 4A)  Metasomal syntergum not covering the entire metasomal surface (Fig. 3F); face without transversal strigae (Fig. 3A)  Metasomal syntergum covering the entire metasoma (Fig. 9C); face with strigae (Fig. 9A, B)  Mesoscutum with microsculpture (only one species with transverse carinae); notauli complete, even if being much larger at the base than close to pronotum (Fig. 9E). Pronotum not projected, striate or with strong irregular carinae (Fig. 9G)