DASTFOGONINAE 



ROBBER FLIES OF THE WORLD 



95 



with only a few scattered hairs medially above and be- 

 hind the vertex; slender bristles begin at the middle 

 of the head and consist of 9 pairs. The proboscis is 

 unusually large; it is distinctly compressed laterally, 

 the base strongly swollen, the medial ridge high and 

 ending at the outer third. At the apex dorsally there 

 is a tuft of long, stiff hairs and laterally a fringe of 

 12 to 15 flat, appressed, long, stiff hairs extending back- 

 ward along the proboscis. Base of proboscis with num- 

 erous, moderately long hairs. Palpus clearly of two 

 segments; first hemicjdindrical and excavated, second 

 attenuate and microporate, each with a few long, stiff 

 hairs ventrally and laterally. The antenna attached 

 at the upper sixth of head and unusually elongate; the 

 first segment is a little longer than the second, the third 

 is twice as long as the first two combined and is rela- 

 tively slender but becomes near the middle a little wider 

 than the second segment and on the outer third it is 

 slightly and gently attenuate. At the apex the third 

 segment bears a short, spoon-shaped microsegment, 

 open dorsally and carrying a distinct short spine. 

 First segment with 8 to 10 bristly hairs below, 2 or 3 at 

 apex above ; second segment with 4 below and 4 above ; 

 third segment with 3 or 4 dorsal setae. 



Head, anterior aspect: The face below antenna one- 

 third of head width and with parallel sides, the sub- 

 epistomal area moderately large and deeply concave 

 but only slightly oblique. The face is micropubescent, 

 sometimes bare in the middle, and with abundant, long, 

 stiff pile over the whole; lower epistomal margin of 

 face with 15 or more pairs of moderately long, weak 

 bristles or stiff hairs. The front extremely short and 

 slightly divergent, the vertex of about the same width; 

 the front bears a number of stiff hairs laterally. Ver- 

 tex rather shallowly excavated; the ocellar protuber- 

 ance is low, gently rounded, and bears a pair of stout, 

 moderately long, divergent bristles to which may be 

 added 1 or 2 pairs of fine hairs. Eye facets enlarged 

 centrally. 



Thorax : The thorax is micropubescent anteriorly and 

 laterally ; most of the pleura pubescent but with a con- 

 spicuous, bare, polished spot on the mesosternopleural 

 area. The mesonotal pile is quite abundant, but fine, 

 curled, flat appressed, short and arises from minute 

 punctures. Acrostical and dorsocentral elements un- 

 differentiated from the remaining pile. Humerus with 

 pile and with 4 short, stout bristles ; notopleural bristles 

 absent. There is a striking fringe of stout, short, tuber- 

 culate bristles above the wing, in all 2 to 4 postalar and 

 no scutellar bristles. Scutellum thick, with abundant, 

 curled, appressed setae. Propleuron with numerous, 

 long, stiff hairs on the lower section and behind, a col- 

 lar with 5 or 6 pairs of weak bristles. The mesopleuron 

 bears widely scattered groups of long, stiff hairs, more 

 or less appressed. Posthypopleuron with 5 long, slen- 

 der hairs and 8 to 10 short, curled hairs. Metapleuron 

 with a wide vertical band of some 16 or more long, 

 weak bristles. Metanotal slopes micropubescent oidy ; 

 metasternum laterally with numerous stiff hairs ; post- 

 535914 — 62— pt. 1 8 



metacoxal area membranous; tegula pubescent only; 

 prosternum not dissociated. 



Legs : All the femora are thickened tlirough the mid- 

 dle; the hind femur massively thickened and strongly 

 swollen, especially beyond the middle. All pile is dense 

 and appressed and setate, except for scattered erect 

 hairs ventrally. The hind femur bears short, stout 

 bristles as follows: 3 dorsomedial beyond the middle, 

 4 dorsal from the middle, 2 middle dorsolateral, and 

 an irregular patch containing 6 lateral bristles beyond 

 the middle ; ventrally there may be 3 or more stout, not 

 tuberculate, spinelike projections towards the apex, with 

 shorter ones opposite and medially. Hind tibia bears 

 6 weak dorsal, 3 or 4 dorsolateral, a strong lateral near 

 the apex, and at. the apex 2 dorsal, 1 lateral, 5 medial, 

 and 4 or 5 ventral bristles. Middle femur with a 

 bristle posteriorly at apex, 2 or 3 anteriorly beyond 

 the middle, and a few fine hairs below ; its tibia has 8 

 dorsal, 5 ventral, 3 or 4 posteroventral bristles, all weak 

 and short. Anterior femur with 3 or 4 posterodorsal 

 bristles on the outer half, 4 to 6 short, weak dorsal on 

 the outer half, and smaller weaker bristles basally; its 

 tibia bears 10 short, distinct anterodorsal, 7 or 8 weak 

 dorsal, 4 moderately long ventral bristles and 7 or 8 

 long, stiff hairs; apex without spine. The tarsi are 

 rather shortened but all the tarsi and especially the 

 basitarsi longer than in Triclioscelhs. The tarsi end in 

 long, large pulvilli, and unusually stout, bladelike em- 

 podium, and claws that are only moderately sharp and 

 are chiefly curved near the apex. 



Wings : The wings are relatively broad, with a dilute 

 pattern. Marginal cell closed at or near the margin, 

 bulbous apically; the anterior branch of the third vein 

 makes a rather sharp, nearly rectangular turn below 

 the end of the marginal cell and ends well above the 

 apex of the wing ; first and fourth posterior cells closed 

 with a short stalk, anal cell closed; veins ending fourth 

 posterior cell and lower distal cell form nearly a 

 straight line; alula large; the ambient vein ends at or 

 near the end of the anal cell. 



Abdomen : The abdomen is robust, with nearly par- 

 allel sides and fully as wide as the thorax : it is strongly 

 convex across the tergites. First tergite scarcely swol- 

 len; six tergites present in the male and the female. 

 Pile of abdomen quite dense and often obscuring the 

 ground color; the pile is also quite flat appressed, 

 except for a few fine, erect hairs laterally on the first 

 two tergites and sparsely on the sternites. Strong 

 bristles are present laterally on all the tergites : 5 pairs 

 on tergite 1 ; 5 or more on tergites 2 and 3 and 4 ; and 

 reduced numbers on the remainder. Male terminalia 

 completely rotate, moderately protuberant and con- 

 spicuous. The epandrium consists of a very large, 

 elongate, highly convex, bulbous or basketlike, unclef t 

 plate with transverse, apex ; the plate is attached below 

 and lies upon the ventral aspect, leaving the interior 

 structures open and exposed from the dorsal aspect. 

 Gonopod prominent, of considerable depth at base, 

 shorter than the epandrial bowl, and with conspicuous, 

 slender, often hood-tipped processes. Hypandrium, if 



