Male. Head black in ground color, face yellowish and gena reddish brown, with grayish pruinosity, frontal vitta black; antenna black; palpus reddish yellow except brownish apex. Frons strongly narrowed upward, 1/15-1/16 head width at the narrowest point; frontal vitta strongly narrowed in front of ocellar triangle and nearly as wide as base of palpus; parafacial slightly widened below, about 4 times as wide as flagellomere 1 at middle height; lower margin of face strongly protruding forward, facial carina high and arched in lateral view, rather rounded on anterior surface; gena 0.4-0.5 eye height. Frontoorbital plate with 1-2 rows of black hairs on lower 1/2; parafacial bare; inner vertical seta fine hair-like, about 1/3 eye height, slightly shorter than postocellar seta; outer vertical seta indistinct; 12-16 inclinate frontal setae, upper 2-3 fine hair-like, lower ones about equalsized and as long as ocellar seta, distinctly longer than inner vertical seta; vibrissa inserted above lower margin of face by about length of pedicel; occiput with dense pale yellowish pile, 2-3 rows of fine black hairs on upper portion. Antennal base slightly above level with lower 1/5 of eye height; antenna falling short of lower margin of face by 0.7-1.0 times length of flagellomere 1; flagellomere 1 2.5-3 times as long as pedicel; arista including plumosity about twice as wide as flagellomere 1. Prementum slender, 2/3-5/6 of eye height; palpus about twice as long as flagellomere 1. Thorax black, with thin grayish pruinosity; dorsum with 5 black longitudinal vittae on presutural area of scutum, inner 3 vittae diffusing marginally, sometimes fused with each other and forming a broad median vitta, on postsutural scutum 3 broad vittae visible, median vitta extending to anterior margin of scutellum; scutellum black in ground color, with grayish brown pruinosity. Five postpronotal setae; 1-2+2 ac, 2-3+3 dc; 0+2 ia; 3-4 sa. Scutellum with subapical seta slightly longer than basal seta and about twice as long as scutellum; apical scutellar seta rather fine, 1.2-1.3 times as long as scutellum. Wing hyaline, faintly and evenly tinged with pale brown; tegula black and basicosta reddish yellow; lower calypter pale brownish; halter yellow, brownish on basal portion. Costal spine absent; relative lengths of costal sections second, third and fourth approximately as 6:11:5; vein M from dm-cu crossvein to its bend about twice as long as distance between the bend and wing margin; cell r4+5 narrowly open. Legs black, pulvilli yellowish. Legs. Fore tibia with 2 p; mid tibia with 1 fine ad, 1 p and 2 pd, without v; hind tibia with 3-4 ad and 2 pd, apical pv short but distinct. Abdomen long ovate, black in ground color, with grayish pruinosity, a square brown median spot present each on tergites 3 and 4. Syntergite 1+2 excavated nearly to posterior margin, without median marginal seta, with 2-3 lateral marginal setae; tergite 3 with 2-4 irregular and rather short median discal setae, 2 median marginal and 2-3 lateral marginal setae, discal setae arranged on posteior portion; tergite 4 with a row of marginal setae and 2-4 irregular median discal setae on posterior portion; tergite 5 with an irregular row of discal and a regular row of storng marginal setae. Sternite 5 nearly square, with many long hairs, median cleft v-shaped and deep, posterior lobe about 4/7 of total length. Male terminalia. Cerci in dorsal view strongly narrowed on apical 1/2, apical portion slender and pointed at apex, in lateral view slightly bent ventrally; surstylus with dense long hairs on outside, with rather sparse hairs on inside, not extending beyond apex of cerci, dorsal margin weakly curved inward, in lateral view wide and weakly and evenly narrowed to blunt apex; postgonite shorter than basiphallus; distiphallus with membranous apical part about 2.5 times as long as sclerotized basal part, with dense minute spinules on entire portion, curved dorsally. Female. Differing from male as follows: Vertex about 1/3 head width; frontal vitta weakly widened anteriorly, about twice as wide as fronto-orbital plate; gena about 0.6 eye height; inner vertical seta strong, about 2/3 eye height and slightly longer than ocellar seta; outer vertical seta about 1/2 as long as inner vertical seta; 1 fine outwardly directed prevertical seta, at most as long as outer vertical seta; 6-8 inclinate frontal setae; 2 strong proclinate orbital setae as long as inner vertical sete; mid tibia with 2 ad, 1 p, 2-3 pd and a strong v; claw and pulvillus shorter than tarsomere 5; abdominal tergite 3 without median discal seta, tergite 4 with or without 2 median discal setae.