342 



UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



dorsolateral row of 3 or 4 black, curved, basally stout, 

 apically sharp bristles. Tarsi blackish, the claws black 

 and sharp, the pulvilli large, broad, and brownish. 



Wings: Male wing grey, rendered considerably 

 darker by dense, black villi everywhere present, except 

 on the basal half of the basal cell. Alula more than 

 twice as along as wide. First posterior cell closed with 

 a short stalk. Stalk of marginal cell quite long, longer 

 than the stalk of the fourth posterior cell. Medial 

 crossvein long, paralleling the upper margin of the 

 discal cell. 



Abdomen : The abdomen is dull black, the first, sec- 

 ond, third, and fourth tergites with remarkably long, 

 extensive, posterior, membranous margins much in con- 

 trast to Rhopalogaster Macquart, where they are quite 

 narrow and of uniform width. In Phellopteron these 

 membranous margins of the second and third tergites 

 are across the middle of the tergites half or more than 

 half as long as the tergite. Pile scanty, appressed, 

 black and setate, with rather abundant, longer, yellow- 

 ish white pile on the sides of the first and second 

 tergites. Bristles absent on all the tergites. In the 

 extreme posterior corner of the first tergite there are 2 

 or 3 slender, short, black, bristly hairs. Terminalia 

 shining black, of the usual form found in Laphriini 

 but unusually short, with the epandrial bowl deep, the 

 gonopod with a posterodorsal, single, leaflike, brown- 

 ish black appendage, having a blunt, slightly expanded 

 apex. 



Type: Male, allotype female, Trelawny, 12 miles 

 south of Falmouth, Windsor Estate, May 14, 1956, col- 

 lected by T. H. Farr. Three paratype males with the 

 same data. Types in the Science Institute, Kingston, 

 Jamaica. Two paratypes in author's collection. 



Genus Nusa Walker 



Figukes 153, 291, 293, 294, 626, 627, 1224, 1233, 1295, 1296, 1304, 

 2077, 2092, 2099, 2102, 2140, 2149 



Nusa Walker, Insecta Saundersiana, vol. 1, pt. 2, p. 105, 1851. 

 Type of genus: Nusa aequalis Walker, 1851. Designated 

 by Hermann, 1912. 



Dasythrix Loew, Benierkungen fiber die Familie Asiliden, p. 21, 

 1851. Type of genus: Dasythrix infumata Loew, 1851, by 

 original designation. 



nalictosoma Rondani, Ann. Mus. Civ. Stor. Nat. Genova, vol. 4, 

 p. 298, 1873. Type of genus : Halictosoma pvella Ron- 

 dani, 1873, by monotypy. 



Medium size flies, characterized by the numerous, 

 strong bristles, but with short, appressed, setate pile. 

 The surface is usually pollinose. The proboscis is 

 comparatively weak, slightly but distinctly compressed 

 dorsoventrally and the small, cylindrical palpus is 

 clearly of two segments. The absence of the ambient 

 vein immediately distinguishes them from Andreno- 

 soma Rondani. The anterior branch of the third vein 

 ends far above the wing apex. The first posterior cell 

 is quite narrow, closed with a long stalk, or sometimes 

 widely open; the medial and cubital veins tend to be 



evanescent towards the wing margin. Mesopleuron 

 posteriorly with stout bristles. Length 12 to 23 mm. 

 Head, lateral aspect : The face is rather prominent, a 

 little more prominent below, due to the recession of the 

 eye, and gently convex ; the eye is narrowed below due 

 to anteroventral recession ; it is strongly convex anteri- 

 orly, gently convex behind or sometimes plane through 

 the middle. The pile of the occiput is rather dense and 

 long and fine ventrally and may extend even to the 

 upper third ; it is replaced near the vertex with distinct 

 bristles which characteristically become very stout and 

 long near the upper corners of the eye, especially behind 

 the vertex, and are rather striking in appearance. The 

 proboscis is comparatively slender and weak, a little 

 swollen at the base on the ventral portion, somewhat 

 more distinctly swollen and gently tapered from the 

 dorsal aspect. It is distinctly though moderately com- 

 pressed apically in a dorsoventral direction. The me- 

 dial ridge is long, extending to the apex but usually low. 

 Proboscis directed obliquely forward or often chiefly 

 downward. Palpus rather small, clearly of two seg- 

 ments, slender and cylindrical ; the first segment is ex- 

 cavated, the second bears apical pile or bristles and is 

 sometimes a little swollen in the middle. 



Antenna attached at or above the upper third of the 

 face, the first segment is stout and robust, a little longer 

 than the second. The third segment is as long as the 

 first two combined or sometimes a little shorter; it is 

 slightly flattened and wider in the middle, gently 

 tapered to base and apex, or sometimes more strongly 

 tapered on the apical half than on the basal part. The 

 apex bears a conspicuous pit containing laterally a vis- 

 ible spine or in some species with a short, microsegment 

 carrying an apical spine ; a microsegment is absent in 

 the type of genus but a spine is present. The pile of 

 the first segment consists dorsally of 3 or 4 fine, slender 

 bristles; laterally and ventrally of 6 or 7 quite long, 

 stout bristles; the second segment bears several slender 

 bristles somewhat shorter dorsally and ventrally. 



Head, anterior aspect : The face below antenna about 

 a third the head width with parallel sides below. Sub- 

 epistomal area large and long, two-thirds as long as 

 the face or longer and strongly oblique, nearly plane 

 and pollinose. The face is pubescent and densely 

 covered through the middle with very stout, long, 

 numerous bristles which include a dorsal, transverse 

 row, containing 2 to 4 pairs, beneath the antenna ; lateral 

 margins of the subepistoma with very stout bristles; the 

 face also carries additional, long, stiff, intermixed pile. 

 Front rather short and pollinose with, in the type of 

 genus, 6 rather stout, long bristles along the eye mar- 

 gin, the number is sometimes increased or reduced and 

 replaced by weaker, slender, bristly hairs. Vertex 

 strongly and deeply excavated in the type of genus but 

 only moderately excavated in some species; the ocel- 

 larium is large and prominent with steep sides bearing 

 in the type of genus a single pair of exceptionally 

 long, very stout, divergent bristles to which is added 



