Stipomorpha tenuicauda (Curran, 1925):339

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.

Ubristes (Ubristes) tenuicaudus (Curran, 1925).

Curran, C.H. (1925) New American Diptera. II. The Annals and Magazine of Natural History (9) 16, 338-354.

Synonym:

Microdon tenuicaudus Curran, 1925: 339.

Adapted from original description (Curran 1925).

Related to M. notata Wiedemann; the abdomen much narrowed behind the second segment; reddish or yellow, except the front, scutum, and part of the metatibiae; scutellum unarmed; eyes bare.

FEMALE.

Head longest below, reddish yellow, the face shining, its pile fairly long, subappressed; front black, the transverse depression deep and wide; width of front equal to one-fourth the head-width, the depression densely, the sides above moderately pilose; pile of head rather golden yellow, whitish on the lower part of the occiput; occiput largely black, greyish pollinose except above. Upper two-thirds of the front much swollen, very prominent, the slightly elongate, small ocellar triangle situated in the middle of the swelling which is rounded in front and behind. Antennae brownish red, pedicel and upper margin of scape brown, black-haired, the lengths as 3:1:5, basoflagellomere with almost parallel sides, of moderate size, rounded at apex; arista shorter than basoflagellomere, rather slender, brown.

Thorax: Scutum black; broad anterior margin, except on the wide middle vitta, the broad lateral margin in front of the suture and behind the root of the wings pale yellowish, the pleura similar except an obscure dark macula on the anepisternum and a distinct brownish macula beneath the calypter. Anterior and posterior borders with erect yellowish pile, elsewhere clothed with appressed golden-yellow hair, except a black-haired triangle above the wings and some strong erect dark hairs connecting the inner ends of the triangles and a few scattered hairs behind. Pleura mostly bare, the anepisternum with erect brassy hair. Scutellum yellow, with erect black hair, the sides with erect yellow hair, the apical margin evenly convex, the disc flat. Legs reddish; metatibiae much thickened, black on the apical half except below, the first two metatarsomeres broadened and black. Pile of legs short, appressed, brassy yellow, a little longer and snow-white on the upper side of the anterior four tibiae, and also longer on the posterior femora; pile very much longer and abundant on the upper side of the metatibiae and first two tarsomeres, whitish on the basal half, elsewhere black, brassy yellow on all the articulations and on the whole of the last three tarsomeres. Wings luteous, more strongly so on the basal half in front. Calypter, the fringe, and the halteres yellow.

Abdomen brownish red, not wider than the thorax, strongly narrowed behind the second segment; first two segments with long, stout, sparse, yellow hairs, the others with abundant short, rather erect, yellow pile.

GenBank accession number for this species are: protein-coding COI gene (AY261710).

These flies appear to be mimics of stingless (trigoniform) bees (Family Apidae, tribe Meliponini).

Body length: 10 mm (Curran 1925).

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

Neotropical species known from Peru and Brazil.