Ubristes (Ubristes) flavitibia Walker, 1852.
Walker, F. (1852) Diptera. Part III, pp. 157-252, pls. 5-6. In [Saunders, W. W. (ed.)], Insecta Saundersiana, or characters of undescribed insects in the collection of William Wilson Sauders, Esq., F.R.S., F.L.S., & c. Vol. 1. Van Voorst, London. 474 pp. [before 1852.08.02]
Ubristes is characterized by the metatibia usually enlarged but always with a brush of long pile on the dorsal edge. The presence or absence of the appendix on vein R4+5 is variable in this group. The group is divided into an number of subgroups (Hypselosyrphus, Stipomorpha, Ubristes) on the basis of the shape of the abdomen (Cheng and Thompson 2008).
Ubristes (Ubristes) species have postmetacoxal bridge complete; abdomen oval or rectangular; metatibia with long pile along dorsal edge, forming a distinct brush of pile; and vein R4+5 with an appendix extending posteriorly into cell R4+5.
Adapted from original description (Walker 1852).
Nigro-aenea, scutello piceo, abdominis apice fulvo, antennis rufis, pedibus piceis, tarsis fulvis, tibiis posticis flavis flavoque hirtis, alis cinereis basi et ad coslam fuscis.
Body black, shining, clothed with black pili; a white macula at the base of the antennae; face thinly clothed with white pili, adorned with two white maculae on each side; eyes black, anterior part nearly flat, its facets a little larger than those elsewhere; mouth pitchy; antennae very dark red; scape clothed above with very short black hairs; gena slightly bronzed; scutellum pitchy; a purple tinge on the posterior part of the scutum; abdomen nearly spindle-shaped, a little narrower and much longer than the thorax; tip dark tawny; legs pitchy, thickly clothed with short black pili; legs dark tawny; claws black, tawny towards the base; foot-cushions pale tawny; hind-shanks pale yellow, thickly clothed with bright yellow hairs; wings gray, dark brown at the base and along two-thirds of the anterior border; wing-ribs pitchy; veins black; poisers pitchy, dark tawny towards the base.
These flies appear to be mimics of stingless (trigoniform) bees (Family Apidae, tribe Meliponini).
Length: body, 11.2 mm (Walker 1852).
Neotropical species known from Guyana and Brazil.
