Spheginobaccha chillcotti Thompson, 1974:274

This genus is readily separated from other microdons by the incomplete metathoracic bridge, round/oval basoflagellomere, occiput with a dorsolateral crease and other characters (see key). The species were revised by Thompson (1974), with additions by Dirickx (1995) (from Cheng and Thompson 2008).

Adapted from original description (Thompson 1974).

MALE.

Head: Antennae with scape and pedicel bluish black, basoflagellomere dark on apical 1/2; basoflagellomere only about one-half longer than first two segments together; eyes almost holoptic in male, separated by a distance less than basal width of arista, approximate for a distance equal to length of scape; dorsal third of occiput dark pollinose, extensively black pilose.

Thorax dark except yellowish tinge on postpronotum and postalar calli; trochanters black; femora black except yellow basal third; tibiae yellow except black apical 2/3 of protibiae, apical 1/3 of mesotibiae and apical 1/2 of metatibiae; legs black pilose; wings more extensively bare, 2nd basal cell bare, narrowly bare on both sides of veins R1, R2+3, R4+5 and M out to apical fourth of wings.

Abdomen black and yellow, medial vitta on 2nd and 3rd terga well developed and expanded on basal margins of terga; 1st segment completely black; lateral and posterior margin of terga black. Male genitalia: surstyli shorter and broader than in other species; 9th sternum pilose all along dorsolaterally surface and on outer prong, without accessory prong; outer prongs slightly asymmetric, directed posteriorly, left outer prong curved ventrally; inner prongs strongly asymmetric, apical position, right inner prong directed posteriorly and left inner prong curved dorsally; membranous pouches only beneath outer prongs and without sclerotized lancets; aedeagus narrow, strongly curved dorsally, with tip recurved.

Spheginobaccha chillcotti Thompson, 1974.

Thompson, F. C. 1974. The genus Spheginobaccha de Meijere (Dipterea: Syrphidae). Transactions of the American Entomological Society 100, 255-287. [1974.11.06]

Spheginobaccha chillcotti may be the unnamed species figured by Hull (1949: 237, figs. A & B) since chillcotti is the only Spheginobaccha known to me with subcontiguous eyes in the male. Hull's figures agree well with chillcotti except chillcotti as well as all other species of Spheginobaccha, has a facial tubercle which is lacking in Hull's figure (error?) (from Thompson 1974).

Length: body, male 10.6 mm; wing, male 8.3 mm (Thompson 1974).

The genus Spheginobaccha was included in the combined analysis by Ståhls et al. (2003) and the morphological analysis of Hippa and Ståhls (2005). In both cases, this genus was resolved as sister group of Microdon and Ubristes.

Holotype collected in Nepal, Katmandu, Balaju, 4,500 ft.