279 

 SOME NEW NEOTROPICAL SIMULIIDAE. 



By Frederick Knab, 



Bureau of Entomology, U.S. Department of Agriculture. 



Dr. Andrew Balfour, Director of the Wellcome Bureau of Scientific Research, 

 has submitted to the writer for study part of the Diptera collected on his recent voyage 

 in the American tropics. A species of Simulium from the valley of the Atrato Rivci- 

 in Colombia proves to be new and is described below. Through the good 

 offices of Dr. Balfour further interesting material was received from K. S. Wise, 

 Surgeon- General for British Guiana, and from F. W. Urich, Entomologist of Trinidad. 

 These lots contained an additional new species of Simulium each, of which the 

 descriptions follow. Diptera belonging to other groups and of economic interest will 

 be treated in subsequent papers. 



Simulium sanguineum, sp. nov. 



Female. — Occiput, frons and face black, with strong blue and green pearly 

 pruinosity and with scattered short black hairs ; frons broad, above nearly one-third 

 the width of head, narrowing slightly toward antennae. Antennae with the three 

 proximal joints ferruginous, the others dull blackish and with fine, appressed pale 

 pubescence. Scutum velvet black, with four broad, pruinose, strongly iridescent, 

 metallic blue stripes, visible only in certain lights ; outer stripes very broad, leaden 

 gray in some lights, on lateral margins and continued along posterior margin ; 

 submedian stripes broad, nearer to each other than to lateral stripes, slightly sinuate 

 and very slightly narrowed beyond the middle. In some lights the submedian stripes 

 nearly disappear and a pair of similarly coloured wedge-shaped spots appear 

 anteriorly in their place, the base of the wedge on anterior margin, its point 

 terminating at about the middle of the disk ; vestiture of long golden hair-scales, 

 evenly distributed and not arranged in rows or groups. Scutellum narrow, 

 subtriangular, velvet-black, with long golden transverse hair-scales and black- 

 bristles on the margin. Postnotum short, black, with pruinosity like that on margins 

 of scutum. Pleurae and coxae black, gray pruinose. Abdomen black, elongate, 

 somewhat constricted beyond base, thickened beyond middle ; first segment dorsally 

 strongly iridescent, the four following ones dull velvet-black and with the flexible 

 basal portion gray ; segments 5 to 8 shining black, highly polished and with a few 

 scattered black bristles. Front legs with the femora luteous and with a brownish 

 shade dorsally ; tibiae luteous, with silvery lustre, the apex very slightly darkened ; 

 tarsi black. Middle legs with the femora and tibiae brownish black, the knees 

 narrowly and the apices of the tibiae yellowish : tarsi with the first joint whitish 

 except at extreme apex, second joint whitish with dark apical ring, the others wholly 

 dark. Hind legs with the femora brownish black, the tibiae white on basal third, 

 black beyond ; tarsi with the first joint white, black on apical fourth, the second 

 joint white, black on apical third, the last three black. Claws simple. Wings hyaline, 

 without iridescent spot in anal field ; coarse veins pale yellow. Halteres pale yellow, 

 black basally. 



Length : Body about 12 mm., wing ]-5 mm. 



