Allobaccha cuthbertsoni (Curran 1938)
Black species with brown stigma and a dark spot on the wing tip, third and seventh veins strongly curved.
Can be confused with A. praeusta and A. sapphirina
Original description in:
Curran, C.H. 1938. Records and descriptions of African Syrphidae II (Diptera). American Museum Novitates 1010.
https://digitallibrary.amnh.org/items/585f6b20-0acb-4778-b38e-174589071418
Black, the legs mostly reddish; wings tinged with brown except basally and with trace of preapical brown spot. Length, about 9 mm.
MALE.-Head metallic blackish blue in ground color, the frontal and vertical triangles shining black; pile black, pale yellow on the occiput, the upper occipital cilia brownish yellow. Frontal triangle rather small, moderately convex, the sides and upper border with pile, the middle bare, a very small spot of cinereous pollen above. Vertical triangle elongate and narrow, the row of hair wholly black. Occiput and face cinereous white pollinose. Oral margin strongly oblique. Face perpendicular, the tubercle of medium size and more prominent than the antennal base, shining black. Antennae reddish, the third segment slightly darkened above, one half longer than wide, subcylindrical, the apex broadly rounded; arista brown on apical half.
Thorax shining black, the pleura with obscure yellowish pollen in the middle and whitish pollen on blackish-blue ground posteriorly. Pile yellowish, black behind the suture except in the middle, very pale on the pleura.
Legs reddish, the coxae, posterior femora except the ends and the posterior tibiae on the apical three-fourths, brown. Pile inconspicuous, pale, mostly black on the posterior femora and tibiae, long and blackish posteriorly on the middle femora.
Wings tinged with brown on the apical two-thirds, the stigma dark brown. Between the tips of the second and third veins there is a narrow brown spot along the costa that quickly merges into the pale field. Squamae and fringe white. Halteres pale yellow.
Abdomen shining black, with opaque markings, the sides of the first segment somewhat bluish. Sides of the second segment narrowed to the basal fourth, thence with parallel sides to the apical fourth which is slightly swollen and bears an incomplete opaque fascia; third segment decidedly longer than wide, increasing in width from the base to apex; fourth segment longer than wide and gently tapering apically; fifth segment three times as wide as long. Third segment with a large opaque triangle occupying the apical half except laterally, the fourth with a large, subopaque triangle extending forward from the apical fourth almost to the base, the fifth with the broad apex bronzed. Pile black, obscure yellowish on the basal two segments, whitish on the sides and broad base of the third, the fourth with a broad basal fascia of appressed, sparse, white pile that is greatly expanded inside the lateral margins but does not reach the sides. Genitalia shining black. Venter bluish, with broad, opaque bands on the apices of the sternites.
Type locality: Maputo, Mozambique
A widespread Afrotropical species, numerous records from South Africa and Zimbabwe.
iNat observation:
https://www.inaturalist.org/observations/148648698
