Stipomorpha Hull

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 67-68

Stipomorpha Hull stat. n. Figs 388-396

Stipomorpha Hull, 1945: 74. Type species: Microdon fraudator Shannon, 1927, by original designation.

Description.

Body length: 6-11 mm. Stingless bee mimicking flies with moderately long antennae and more or less triangular abdomen. Head slightly wider than thorax. Face in profile straight to convex; narrower to wider than an eye. Lateral oral margins hardly to moderately produced. Vertex flat, convex or irregularly swollen. Occiput narrow ventrally, slightly widened dorsally. Eye bare. Eye margins in male converging at level of frons, with mutual distance 1-3 times width of antennal fossa. Antennal fossa about as wide as high. Antenna shorter to longer than distance between antennal fossa and anterior oral margin; basoflagellomere shorter to longer than scape, oval; bare. Postpronotum pilose. Scutellum semicircular, sometimes weakly sulcate apicomedially; without calcars. Anepisternum convex, without sulcus; anterodorsally pilose, posteriorly pilose or bare, widely bare in between. Anepimeron with pile limited to dorsal half, if pilose on ventral half then only sparsely. Katepimeron convex; bare. Wing: vein R4+5 usually with posterior appendix (seldomly missing); vein M1 perpendicular to vein R4+5; postero-apical corner of cell r4+5 widely rounded to rectangular, with or without small appendix; crossvein r-m located between basal 1/5 to 1/3 of cell dm. Abdomen widest at tergite 2, with next tergites either gradually narrowing (kite-shaped abdomen) or more or less parallel-sided; 1.5 to 3.5 times as long as wide. Antetergite almost fused to tergite 1; in most species enlarged, concave and smooth. Tergites 3 and 4 fused. Sternite 1 bare. Male genitalia: phallus unfurcate, bent dorsad, in most species projecting beyond apex of hypandrium; hypandrium with bulb-like base; epandrium without ventrolateral ridge; surstylus in most species with two wide lobes, but other shapes also occur.

Diagnosis.

Sternites 2 and 3 separated by membraneous part as wide as or wider than sternite 2.

Discussion.

When Hull (1945) erected Stipomorpha as a subgenus of Microdon , he did so based on the shape of the abdomen: "...the first two abdominal segments greatly flared and flattened and wider than the thorax; remainder of the abdomen immediately compressed into a rounded, subcylindrical pipe-like form." Shortly after, Hull (1949) ranked Stipomorpha as a subgenus of Paramixogasteroides Shiraki, 1930, without stating a reason for this. Subsequent authors have regarded Stipomorpha as synonymous with Ubristes . See under Ubristes for a discussion on the relationship between these groups, which are here considered as separate genera. Stipomorpha as presently defined contains most species listed under Ubristes by Thompson et al. (1976).

Diversity and distribution.

Described species: 16. Descriptions of nine additional species are in preparation by the first author. Neotropical, with records ranging from Costa Rica to Argentina.