Bardistopus Mann

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 21-22

Bardistopus Mann Figs 35-37

Bardistopus Mann, 1920: 61. Type species: Bardistopus papuanum Mann, 1920: 61, by original designation.

Description.

Body length: 6-7 mm. Small, dark flies with very long antennae and oval abdomen, which in lateral view appears constricted. Head slightly wider than thorax. Face evenly convex. Lateral oral margins not produced. Vertex flat. Occiput ventrally narrow; dorsally slightly widened. Eye bare. Eyes in male not converging at level of frons; mutual distance much larger than width of antennal fossa. Antennal fossa about as high as wide. Antenna longer than distance between antennal fossa and anterior oral margin. Basoflagellomere about six times as long as scape. Postpronotum bare. Scutellum semicircular; without calcars. Anepisternum without sulcus; pilose anteriorly and posteriorly, widely bare in between. Anepimeron pilose on dorsal half, bare on ventral half. Katepimeron flat; pilose. Wing: vein R4+5 with posterior appendix; vein M1 perpendicular to vein R4+5 and vein M; crossvein r-m located around basal 1/7 of cell dm. Abdomen oval in dorsal view, but in lateral view appearing constricted due to flattened segment 2. Tergites 3 and 4 fused. Male genitalia: phallus furcate, with furcation point in apical half, strongly bent dorsad; epandrium without ventrolateral ridge; surstylus elongate, bent dorsad.

Diagnosis.

Vein R4+5 with posterior appendix. Postpronotum bare. Abdomen in dorsal view oval; in lateral view constricted at segment 2. Basoflagellomere about six times as long as scape.

Discussion.

No statements about taxonomic affinities of Bardistopus have been made previously, except Cheng and Thompson (2008) who wrote that the name was 'established for a Microdon species, which has a greatly elongate basoflagellomere’. Clearly the taxon does not belong to Microdon , because of the long basoflagellomere and the structure of the male genitalia (apically furcate phallus). These characters, combined with the bare postpronotum, suggest it might be related to Paramixogaster . However, the phylogenetic analysis of morphological characters by Reemer and Ståhls (in press) place it as a sister group of a clade containing taxa of which the male has a furcate basoflagellomere: Schizoceratomyia , Furcantenna and Carreramyia . Future studies employing molecular data could help elucidate the phylogenetic affinities of Bardistopus .

According to Mann (1920) the type specimens of the type species are females, but actually both are males (coll. USNM).

Diversity and distribution.

Described species: 1. Solomon Islands: Ugi.