All specimens have been reared from peyote, Lophophora williamsii (Cactaceae).
Differs from other member of the aethiops-group in the combination of silvery microtomentose face, subshiny mesonotum, 3+1 dc and 1 prsc.
Male coloration and vestiture: frons subshiny to shiny black, ocellar triangle slightly brown microtomentose, orbital plates subshiny to shiny, lunule black, basoflagellomere basomedially yellow, face silvery microtomentose, palpus brown; thorax with mesonotum subshiny (very slightly brown microtomentose), scutellum and pleura brown microtomentose except for shiny spot on an- and katepisternum, wing hyaline, veins light brown, brown spot at tip of vein R1 absent, calypter hyaline, halter black, legs black; abdomen with T2-4 brown microtomentose except for shiny posterolateral corners, T5 shiny black except for microtomentose anterior margin. Female coloration and vestiture: palpus yellow, halter yellow, abdomen with T2-4 and anterior margin of T5 brown microtomentose, tip of T5 shiny.
Morphology. Head: frons with 2 orbital and 2+0.5 frontal setae, middle frontal seta medioreclinate. In males frons ?x as wide at posterior margin than at base of antenna, arista about 3.6x as long as basoflagellomere wide, pubescence on arista very short, posterior eye margin without notch, gradually separating from head margin ventrally.
Thorax: 3+1 dc, 1 prsc, 1 pprn, 1+0.6 prs and row of short setae, 1+0.8+0.7 keps setae, posterior prsc about as long as posterior dc, seta between posterior prsc and posterior dc present. Wing with vein R4+5 and M1 converging (3.3), and ultimate section of vein M1 1.6x as long as penultimate section. Fore femur slightly stronger setulose, tibial organ absent.
Male abdomen: posteromedial triangular projection of T1 into T2 absent. Tergal chaetotaxy: T2 anterolateral corner with more than 3 lines of setae, T2-5 setulose. S5 1.3x as long as wide, 1.2x as long and 1.0x as wide as S4, roughly triangular with posterior margin indented, posterior 2/3 setulose (Pl. 2I). Male genitalia with apical seta on cercus as long as longest epandrial seta, 1 seta on subepandrial plate, surstylus 0.8x as long as epandrium high, dilated apically (1.7x), bent posteriorly, 7.3x as long as wide, structure of lateral surface smooth, medial surface without setulae.
Special characters: female palpus enlarged and bright yellow.
Body length: 2.9 mm; wing length: 2.9 mm.