Rhoga Walker

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 60-61

Rhoga Walker Figs 327-331

Rhoga Walker, 1857: 157. Type species: Rhoga lutescens Walker, 1857: 157, by monotypy.

Papiliomyia Hull, 1937a: 27. Type species: Papiliomyia sepulchrasilva Hull, 1937: 28, by original designation. For synonymy see Hull (1949).

Description.

Body length: 5-10 mm. Stingless bee mimicking flies with short to moderately long antennae and oval, kite-shaped or more or less parallel-sided abdomen. Head slightly wider than thorax. Face convex; narrower than an eye. Lateral oral margins not produced. Vertex narrow, convexly produced and shining in most species, flat in some. Occiput wide and parallel-sided over entire length. Eye with short, sparse pile. Eye margins in male not converging at level of frons, with mutual distance 2 to 3 times as large as width of antennal fossa. Antennal fossa about as wide as high. Antenna as long as or shorter than distance between antennal fossa and anterior oral margin; basoflagellomere shorter to longer than scape, oval; bare. Postpronotum pilose. Scutellum semicircular, in some species weakly sulcate apicomedially; without calcars. Anepisternum without sulcus; pilose anterodorsally and posteriorly, widely bare in between. Anepimeron entirely pilose. Katepimeron convex; bare. Metapleurae either separated or forming postmetacoxal bridge. Wing: vein R4+5 without posterior appendix; vein M1 perpendicular to vein R4+5; postero-apical corner of cell r4+5 rectangular, with small appendix; crossvein r-m located within 1/4 of cell dm, usually within basal 1/10. Abdomen oval or kite-shaped, 1.5 to 2.5 times as long as wide. Tergites 3 and 4 fused. Sternite 1 pilose or bare. Male genitalia: phallus furcate near apex, with dorsal and ventral process equally long; epandrium without ventrolateral ridge.

Diagnosis.

Vein R4+5 without posterior appendix. Occiput widened and parallel-sided over entire length.

Discussion.

In some species (e.g. Rhoga mellea (Curran, 1940), Rhoga maculata (Shannon, 1927)) the metapleura are separated and do not form a postmetacoxal bridge. So far in Microdontinae , this character state was known only in the genus Spheginobaccha ( Cheng and Thompson 2008).

The type specimen of the type species, Rhoga lutescens Walker, 1857, is not present in the BMNH-collection (pers. comm. N. Wyatt), where it is supposed to be according to Thompson et al. (1976) and Thompson (2010). Apparently it is lost.

Diversity and distribution.

Described species: 5. Central and South America. Several undescribed species are known to the first author.