DASYPOGONINAH 



ROBBER FLIES OF THE WORLD 



209 



below, bristly or pilose throughout and the proboscis 

 short. Related to Ilabropogon Loew and separated by 

 the slender pulvilli of reduced length, the more slender 

 antenna and the short, robust form. From Pycnopo- 

 gon Loew and Heteropogon Loew it is separated by 

 the parallel sides of the front and vertex. In general 

 appearance it is not unlike some of the medium size, 

 short pilose species of Heteropogon with short abdomen. 

 Length 7 to 9 mm. 



Head, lateral aspect : The face is very short, distinctly 

 convex, and receding below. The eye is rather long, 

 strongly convex anteriorly, plane on the portion lying 

 above the middle, except near the vertex, where it is 

 strongly rounded. The lower two-fifths of the posterior 

 margin is anteroventrally recessive but rounded. The 

 occiput is only moderately thick, a little more extensive 

 below. The occipital pile is rather scanty, a little more 

 abundant below, longer and fine ; it is absent from the 

 middle and upper portion and replaced by double row of 

 slender, bristly hairs or very weak bristles ; behind the 

 upper eye corners this row is trebled. The proboscis 

 is short, relatively stout, obtusely rounded at the apex, 

 and subcylindrical but it is apparently higher than wide, 

 because of a long, low, medial ridge. The apex bears 

 fine, bristly pile, but the base below has only 3 or 4 long, 

 fine hairs. Proboscis directed chiefly forward and 

 very little longer than the face. Palpus minute, cylin- 

 drical and short, composed of two segments; the first 

 segment is excavated. Antenna attached quite at the 

 middle of the head, rather elongate, comparatively 

 slender; the first two segments are of nearly equal 

 length, with both short. The first is rather convex and 

 protuberant ventrally, straight dorsally. The third 

 segment is nearly or quite as wide as the second and 

 of uniform width except near the immediate apex, where 

 it is slightly narrowed ; it is a little more than iy 2 times 

 as long as the first two segments and bears a moderately 

 long, stout microsegment which is directed downward 

 and carries an apical spine. 



Head, anterior aspect: The face below antenna is 

 about one-fourth of the head width and divergent be- 

 low. The vertex is very nearly the same width as the 

 upper face. Subepistomal area is small and short, 

 nearly horizontal. The face is quite thinly micropubes- 

 cent with abundant, slender, bristly pile ; the epistomal 

 margins of the lower face with 2 pairs of very slender 

 bristles. The front is flat, micropubescent with 5 or 6 

 fine hairs laterally; vertex moderately excavated with 

 slanting sides, the ocellarium large, only moderately 

 high but with steep sides and considerably lower than 

 in Pycnopogon Loew. It bears in the middle 3 pairs 

 of slender bristles or bristly hairs and 3 pairs of shorter 

 hairs behind the ocelli. Anterior eye facets strongly 

 enlarged. 



Thorax: The pleuron is partly bare, with micro- 

 pubescence or pollen on the lower propleuron, upper 

 mesopleuron, posterior sternopleuron, the hypopleuron, 

 and the metapleuron. Mesonotum with a large, bare 

 area but characteristically with vittae or fasciae of 

 micropubescence. The pile of the mesonotum is abun- 



dant but long, fine and bristly, the elements curled back- 

 ward; there is a double row of acrostical elements 

 present, but dorsocentral bristles or hairs are not differ- 

 entiated ; the pile in front of the scutellum may be some- 

 what longer across this entire area. Humerus with 8 or 

 10 long, stiff hairs. The lateral margins of the mesono- 

 tum may have the following complement of long, stout, 

 pale bristles : 2 notopleural, 1 supraalar, 1 postalar, and 

 6 pairs on the scutellum. Scutellum convex, with an im- 

 pressed rim, bare, except along the base, which is micro- 

 pubescent and the whole structure apilose. Propleuron 

 with rather scanty, fine pile; bristles absent on the 

 collar, but with 2 or more distinct, long, slender bristles 

 on the posterolateral pronotum. The mesopleuron is 

 strongly protuberant, villose, rather rounded and dome- 

 like, the upper half pubescent with abundant, long, fine 

 pile but no bristles. Anterior and posterior upper 

 sternopleuron both pubescent and pilose; pteropleuron 

 and hypopleuron apilose; metapleuron with a narrow, 

 vertical band of 15 or more long, slender bristles or 

 bristly hairs which are bent and curved distally; the 

 lateral metanotum is micropubescent only ; tegula with 

 setae ; basalare micropubescent only ; lateral and ventral 

 metasternum with pile; postmetacoxal area mem- 

 branous. 



Legs: The femora are stout without being swollen; 

 the dorsal pile is fine, setate, and subappressed. The 

 following complement of bristles may be present on 

 the hind femur, 6 lateral, 1 subapical dorsolateral, 1 

 dorsal and 1 dorsomedial, besides a ventrolateral row 

 of bristly hairs and a ventral row partly doubled and 

 trebled basally ; these ventral elements consist of longer, 

 slender, bristly hairs or weak bristles. This tibia has 

 2 dorsal bristles on the outer half, with 5 lateral and 3 

 slightly longer, ventrolateral bristles at the middle and 

 beyond, and 1 similar bristle hair basally ; the apex has 

 short, stout bristles, 1 dorsomedial, 4 medial, 3 ventral, 

 1 ventrolateral, and 1 dorsolateral. Middle femur with 

 4 anterior bristles and 4 bristles posteriorly near the 

 apex and with a row of ventral and posteroventral 

 hairs. This tibia with 4 or 5 anterodorsal bristles, 3 or 

 4 posterodorsal, and 7 comparatively long posteroven- 

 tral bristles, besides 3 still longer ventral bristles. An- 

 terior femur with a single, long, stout, posterodorsal 

 bristle at the outer fourth ; its tibia has 6 or 7 short an- 

 terodorsal, a like number of posterodorsal, 6 posterior, 

 and 5 or 6 posteroventral bristles, besides 2 long, ventral 

 bristles near the middle. Apex of anterior tibia with- 

 out spine. Claws slender, sharp, curved from the base, 

 with narrow pulvilli extending to the outer third of 

 the claws ; the empodium is short and slender, the hind 

 claws sometimes very strongly curved and arched with 

 exceptionally slender, narrow pulvilli. 



Wings: The marginal and all of the posterior cells 

 are widely open, the anal cell narrowly closed ; the an- 

 terior crossvein enters the discal cell in the middle, the 

 second basal cell ends in 3 veins, the middle vein short. 

 There is a tendency for a minute nodular spur to be 

 present near the base of the second submarginal cell; 



