560 



XHSriTED STATES NATIONAL MUSEUM BULLETIN 2 24 



Stizolestes, new genus 

 FiouKES 310, 773, 1528, 1537, 2177, 2211, 2351, 2407, 2410 



Type of genus: Asilus nigriventris PMlippi, 1865. 



Kather less than medium size flies with abundant, 

 long, fine pile and the bristles long but slender. The 

 face is narrow and protuberant below. Base of wings 

 whitish in males only. Length 16 mm. 



Head, lateral aspect: The head length is normal; 

 the face is barely visible on the upper third but at this 

 point rather abruptly protrusive ; the remaining lower 

 portion is prominent, protuberant, and convex. Eyes 

 strongly convex anteriorly with a nearly straight pro- 

 file behind over the middle portion. Occiput thick and 

 continuing so nearly to the vertex ; it bears extremely 

 long, stiff, black pile, extending in a wide band from 

 or near the eye margin over the upper three-fourths 

 of the occiput, without true bristles. All this pile is 

 black but the ventral fifth of the occiput has long, fine, 

 tufted, dense, pale yellow pile which obscures the 

 ground color. The proboscis is rather small, subcylin- 

 drical, and slightly swollen towards the base ; the apex 

 is bluntly rounded with a few, fine hairs, the base be- 

 low has some long, fine pile and it is directed chiefly 

 downward. Palpus of one segment, slender, with 

 numerous, long, stiff, black hairs at the apex. The 

 antenna is rather long and slender; the first segment 

 is twice as long as the second. The third segment, style 

 excluded, is a little longer than the first two segments 

 combined. This third segment is quite slender, sub- 

 cylindrical, widest at base, but nowhere as wide as the 

 second segment ; it is gently and slightly attenuate and 

 bears at the apex an obliquely directed, short style at- 

 tached to a very short microsegment. Style half as 

 long as third segment. 



Head, anterior aspect: The face below the antenna 

 is an eighth of head width, strongly divergent and more 

 than twice this width below. Subepistomal area large, 

 oblique, nearly plane and pubescent. The face is pubes- 

 cent with dense, long micropubescence laterally above 

 but without pile ; the middle of the protuberant portion 

 bears a wide, dense, vertical band of extremely long, 

 slender bristles, the upper ones are curved and directed 

 forward, the lower ones directed obliquely downward. 

 Sides of subepistoma with a fringe of more slender 

 bristles. The front is distinctly divergent and bears 

 an extensive patch of long, fine hairs; vertex conver- 

 gent, shallowly excavated, the ocellar protuberance low, 

 abrupt and with 7 or 8 pairs of fine, long hairs. Cen- 

 tral eye facets enlarged. 



Thorax : The thorax is poUinose including the pleu- 

 ron. The mesonotum is strongly convex and abrupt 

 anteriorly, sloping behind. The mesonotal pile is 

 scanty, quite fine and restricted to the dorsocentral ele- 

 ments which are laterally expanded to the humerus and 

 along the lateral margins. There is a double, irregular 

 row or narrow band of long, manelike, slender, thick- 

 set, acrostical bristles; the dorsocentral elements pos- 

 teriorly become extremely long but remain slender ; they 



are numerous and the long, stiff, bristly pile medially 

 in front of the scutellum is dense. There is a bare 

 stripe on each side of the acrostical elements. Humerus 

 with fine pile only ; thef e are 2 notopleural, 1 supraalar, 

 2 postalar, and 5 pairs of exceedingly long, slender scu- 

 tellar bristles. Scutellum thick, with shallowly concave 

 margin; the surface is pollinose with abundant, long, 

 fine, erect pile. Propleuron with long, fine, scattered 

 pile on the upper portion but the anterior ventral ele- 

 ment has a dense tuft of delicate, whitish pile. Prono- 

 tum with stiff hairs but no bristles. The upper border 

 of the mesopleuron, its posterior half, a large patch on 

 the pteropleuron and upper sternopleuron each with 

 niunerous, very long, fine hairs. Hypopleuron and 

 metapleuron both with a vertical band of extremely 

 long, stiff, bristly hairs, some of which might be con- 

 sidered very weak bristles. Hypoplem-on with differ- 

 entiated patch spot. Metanotal slopes with abundant, 

 long pile which is longer and even more abundant 

 on the ventral metasternum ; postmetacoxal area mem- 

 branous; tegula with 2 stiff hairs; posterior basalare 

 with 2 or 3 stiff hairs; squama with a multiple fringe. 

 Legs : The hind femur is rather slender and slightly 

 elongate; anterior four femora slightly thickened bas- 

 ally; all bristles black, rather long, stout basally but 

 tending to be slender and fine apically. Hind femur 

 with short, appressed setae doreally and fine, erect pile 

 below ; it bears a medial apical bristle, a strong dorso- 

 lateral a short distance back from the apex ; 2 or 3 ex- 

 tremely fine, lateral ; 4 stout, long, ventrolateral ; and 5 

 to 7 still longer ventral bristles. Hind tibia with only 

 appressed setae and a brush of setae beginning at the 

 basal third; bristles consist of 3 dorsal, 4 dorsolateral, 

 and 3 ventrolateral bristles begimiing at the middle; 

 apex with 1 dorsal, 2 anterior, 3 medial, 3 ventral 

 bristles. Middle femur with 2 posterior apical, 2 very 

 stout anterior at basal third and just beyond the 

 middle ; and also 4 long, stout, ventral bristles. Middle 

 tibial bristles are quite long and attenuate and consist 

 of 7 posterior, 5 anterior, 1 stout ventral bristle placed 

 at the outer fifth ; ajjical circlet of 10 bristles ; consider- 

 able long, fine, erect pile considerably increased in 

 quantity on all sides except anteriorly. Anterior tibia 

 with 4 short dorsal, 2 posterodorsal, 3 to 6 extremely 

 long, attenuate posteroventral and a few other long, 

 fine hairs and long, anteroventral elements and with a 

 setate brush; apex with 14 bristles. Tarsi have long 

 pulvilli, sharp claws; empodium only half as long as 

 claws. 



Wings : The marginal cell is closed with a long stalk ; 

 the anterior branch of the third vein ends at wing apex ; 

 the second submarginal cell is narrowed from behind ; 

 fourth posterior cell closed and petiolate, convex an- 

 teriorly and distally ; the second basal cell ends in two 

 veins; anal cell closed; alula large, ambient vein com- 

 plete. Male wings white on the basal third. 



Abdomen: The abdomen is cylindroid, scarcely ta- 

 pered, except at base; that of female slightly more 

 tapered. Firet tergite moderately swollen laterally. 

 Pile of abdomen rather short, fine and erect, but ex- 



