Paramixogaster Brunetti

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 53-54

Paramixogaster Brunetti Figs 269-284

Paramixogaster Brunetti, 1923: 319. Type species: Paramixogaster vespiformis Brunetti, 1923: 320, by original designation.

Paramixogasteroides Shiraki, 1930: 8. Type species: Myxogaster variegata Sack, 1922: 16, by original designation.

Tanaopicera Hul, 1945: 76. Type species: Ceratophya variegatus Walker, 1852: 220, by original designation.

Description.

Body length: 5-13 mm. Slender flies with constricted abdomen and long antennae, usually with black and yellow colour pattern, wasp mimics. Head wider than thorax. Face convex in profile; narrower than to wider than an eye. Lateral oral margins not produced. Vertex flat to strongly swollen. Occiput ventrally narrow, dorsally widened. Antennal fossa about as wide as high. Eye bare. Eye margins in male parallel, not converging at level of frons. Antenna longer than distance between antennal fossa and anterior oral margin. Basoflagellomere usually much longer than scape, except shorter in Paramixogaster illucens (Bezzi) and Paramixogaster luxor Curran (see Discussion); bare. Postpronotum bare. Mesoscutum with transverse suture usually incomplete, except complete in Paramixogaster contractus , Paramixogaster conveniens and Paramixogaster omeanus (see Discussion). Scutellum semicircular; without or with small calcars. Anepisternum convex or sulcate; entirely pilose or partly bare on ventral half. Anepimeron entirely pilose. Katepimeron convex; bare. Wing: vein R4+5 with or without posterior appendix; vein M1 perpendicular to vein R4+5 and vein M; postero-apical corner of cell r4+5 rectangular to somewhat acute, with small appendix; crossvein r-m located within basal 1/4 of cell dm. Abdomen elongate, at least 3 times as long as wide; constricted, with narrowest point at tergite 2 and widest point at tergite 3 or 4. Tergites 3 and 4 fused. Male genitalia: phallus furcate, with furcation point in distal 1/3; epandrium without ventrolateral ridge; surstylus weakly furcate, only in Paramixogaster luxor consisting of three distinct branches.

Diagnosis.

Postpronotum bare. Basoflagellomere at least three times as long as wide. Posterio-apical corner of wing cell r4+5 rectangular or somewhat acute. Abdomen usually constricted (i.e. with narrowest point at tergite 2 and widest point at tergite 3 or 4); if not, then the following three characters apply: 1) basoflagellomere 2-4 times as long as scape, 2) tergite 2 less than half as long as tergites 3 and 4 together, 3) face smooth medially (without vitta of transversely wrinkled texture).

Discussion.

Cheng and Thompson (2008) regarded Paramixogasteroides Shiraki, 1930 and Tanaopicera Hull, 1945 as subjective synonyms of Paramixogaster . Examination of the type species of Tanaopicera , Ceratophya variegata Walker, 1852, confirmed this opinion with regard to Tanaopicera . One of the characters Hull (1945) used to characterize Tanaopicera was 'the high, greatly developed vertex’. However, the vertex in the holotype of Ceratophya variegata is neither high nor greatly developed. This species is very similar to other Paramixogaster -species in all important characters. The type species of Paramixogasteroides , Myxogaster variegata Sack, was not examined, but its description by Sack (1922) is clear enough to include this taxon in Paramixogaster .

Morphological variation among the species presently included in Paramixogaster is large. Although most species have a constricted abdomen in dorsal view, this is not the case in the African taxa Paramixogaster acantholepidis (Speiser, 1913) and Paramixogaster crematogastri (Speiser, 1913), and the Australian species Paramixogaster praetermissus (Ferguson, 1926). However, tergite 2 is dorsoventrally flattened in these species, so in lateral view their abdomen appears constricted. In all other important characters of external morphology and male genitalia these taxa belong in Paramixogaster , as corroborated by the results of the phylogenetic analysis based on morphology ( Reemer and Ståhls in press).

Paramixogaster illucens (Bezzi, 1915) and Paramixogaster luxor (Curran, 1931) are the only species included in this genus in which the basoflagellomere is shorter than the scape. In Paramixogaster luxor , the shape of the surstylus also differs from the other species, as it consists of three separate branches (Fig. 282). Nevertheless, both species are included in Paramixogaster because agree with the diagnosis.

Paramixogaster contractus (Brunetti, 1923), Paramixogaster conveniens (Brunetti, 1923) and Paramixogaster omeanus (Paramonov, 1957) are aberrant from all other known species of Paramixogaster in their complete transverse suture. This character is also found in Indascia , which includes species which look superficially similar to these Paramixogaster -species. However, these species are here assigned to Paramixogaster , based on the phylogenetic analysis of their morphology ( Reemer and Ståhls in press). In addition, they possess a diagnostic character for Paramixogaster : the bare postpronotum. The first two species, Paramixogaster contractus and Paramixogaster conveniens , differ from all other studied species of Microdontinae in the presence of pile on the metaepisternum. It will be interesting to re-evaluate their taxonomic affinities when additional material becomes available. At present, the species are only known from the holotypes, which both are females, so no characters of male genitalia or DNA could be analyzed.

As a consequence of transferring some species from other genera to Paramixogaster , replacement names had to be chosen for two species. Examination of the type of Microdon vespiformis de Meijere, 1908 made clear that this is a species of Paramixogaster . As Mixogaster vespiformis Brunetti, 1913 was later designated as the type species of Paramixogaster , these two names are now secondary homonyms. For the junior name, vespiformis Brunetti, the nomen novum Paramixogaster brunettii is proposed here. The other new name introduced here is Paramixogaster sacki for Paramixogasteroides variegata Sack, 1922, which is a junior secondary homonym of Ceratophya variegata Walker, 1852.

Diversity and distribution.

Described species: 26. Afrotropical (5 species), Oriental (12) and Australian region (9). Several additional species, from all three regions, await description.