DASTPOGONINAB 



ROBBER FLIES OF THE WORLD 



33 



is two to three times as long as the second segment. 

 The third segment is more than twice the combined 

 length of the first 2 segments and consists of a long, 

 slender structure which is a little compressed laterally 

 and with an annular base and is divided into 3 parts or 

 subsegments. The third segment, without microseg- 

 ment, is as long as the 2 terminal subsegments or may be 

 longer. Each microsegment is inserted between a pair 

 of winglike, lateral processes extending from the apex 

 of the preceding section or portion of the third seg- 

 ment. Apex of each subsegment with coarse, dense, 

 short pubescence. 



Head, anterior aspect: The face is wide, slightly 

 wider below, more or less shining with both transverse 

 and longitudinal wrinkles, or fine impressed lines. 

 There is very little micropubescence and such as is 

 present is confined to the eye margin and lower face. 

 Pile absent. Bristles restricted to 2 or 3 closely adja- 

 cent rows of moderately long, stout, pale, thickset ele- 

 ments situated transversely immediately above the 

 epistoma. Subepistoma large, slightly oblique, con- 

 cave. Cheeks short. The front is prominent, pol- 

 ished, largely bare with a tuft of short, stiff hairs in 

 front of each antenna. Anterior half of front swollen 

 and protuberant. Eye margin with 7 anteriorly 

 directed, somewhat appressed bristles, 4 of which are 

 quite stout. The vertex is slightly narrowed but not 

 conspicuously. Ocellarium large, wide and of mod- 

 erate height with large ocelli and a row of 3 or 4 short 

 bristles or bristly hairs on each side between the ocelli. 



Thorax: The thorax is prominent and moderately 

 arched, uniformly from front to rear and rather 

 densely beset with flat appressed, short, sharp, undif- 

 ferentiated setae, each with a microtubercle at the base. 

 There are no bristles anywhere on the thorax. A few 

 erect hairs are present on the postalar callosity, some 

 sparse, appressed setae on the mesopleuron, sterno- 

 pleuron, hypopleuron and the pronotum and meta- 

 pleuron with a few fine, long hairs more numerous on 

 the former. Scutellum thick and obtusely convex with 

 scattered, appressed setae. Prosternum fully dissoci- 

 ated. Postmetacoxal area membranous, lateral meta- 

 sternum with long, fine hairs. 



Legs : All the femora are stout, the hind pair a little 

 swollen gradually on the distal half. The first 4 

 femora are a little swollen on the basal half and quite 

 stout distally. All the legs have rather abundant, fine, 

 appressed setae throughout. Hind femur on the basal 

 third with a doubled and partly trebled row of quite 

 short but very stout, spinous bristles or short spines; 

 there may be at least 20 such. Hind tibia with very 

 short, scanty, spinous bristles situated chiefly distally 

 but with a few on the basal half; there are 4 dorsolat- 

 erally and 4 to 6 ventral elements. The hind tibia are 

 stout throughout but also gradually become widened 

 distally. The basitarsus is unusually robust and 

 rather short, yet is nearly as long as the next 3 seg- 

 ments, which are quite stout and short. Apex of hind 

 tibia with 14 short bristles, almost all of them on the 

 ventral half. Middle femur with 8 to 10 moderately 



long, stout, posteroventral bristles on the basal half, 

 a few short ventral bristles distally and with a charac- 

 teristic cluster of rather dense, curved, sharp spines or 

 spinous bristles anteriorly near the base. Those of 

 the cluster which are more distal are shorter in length. 

 Middle tibia with a ventral row of 5 exceptionally 

 slender bristles or bristly hairs and 6 or 7 short, pos- 

 terior bristles, a like number of still shorter postero- 

 dorsal bristles. 



Anterior femur with 7 or 8 moderately long, coarse, 

 ventral bristles on the basal half; its tibia is rather 

 similar to the middle tibia and without spine at apex. 

 Anterior basitarsus, like all the other basitarsi, is quite 

 short and robust and equals the combined length of the 

 next 2 segments. Claws stout, sharp, bent only at apex ; 

 pulvillus large, broad ; the empodium sharp, bladelike, 

 strongly swollen at the base. 



Wings : The wings are generally strongly tinged with 

 brown or bluish black. Marginal cell widely open ; the 

 second submarginal cell is rather wide at base but arises 

 as an arch and often has a spur vein extended towards 

 the base. The anterior branch of the third vein curves 

 forward to end just above the wing apex; the posterior 

 branch ends a considerable distance behind the apex 

 and the first posterior cell is narrowed but open. Third 

 posterior cell either narrowly open or closed with a 

 short stalk. Anal cell closed and stalked. Posterior 

 cross vein present, the nearly rectangular anterior cross- 

 vein enters the discal cell at or just beyond the middle. 

 All the veins are exceptionally stout ; the ambient vein 

 is complete ; alula well developed but hemicircular ; en- 

 tire wing villose. 



Abdomen : The first segment is a little wider and com- 

 paratively short. It is nearly or possibly equally wide 

 as the mesonotum. Sides of abdomen parallel through 

 most of its length or nearly, therefore the abdomen is 

 comparatively broad and robust. It is shining, with 

 scanty, fine appressed, setate pile, a little more abundant 

 on the terminal segment. Sides of first segment with 

 2 or 3 pairs of slender bristles and a little long, coarse 

 hair. Males with 8 segments but the eighth segment 

 reduced to a short, dorsal, liplike protrusion from be- 

 neath the quite short seventh tergite. Females with 8 

 tergites, but the last two are short. Male terminalia 

 moderately large and obtuse. The epandrium has a 

 deep, almost circular sulcus which encloses the short, 

 protruding proctiger and then turns downward and also 

 inward toward the median line ; the two portions do not 

 meet. The posterior portion of the epandrium, there- 

 fore, is obtuse and downturned and reminds one of 

 Heteropogon Loew. Hypandrium extremely short and 

 almost concealed. Gonopod large, swollen, and 

 widened towards the base, with a slender, terminal, 

 hooked process and with a much longer, straight, 

 pronglike dorsal process. Female with the terminalia 

 very short, recessed within the posterior cavity, without 

 spines. Eighth sternite with a prominent, thin, gently 

 rounded, lateral, flaf>like extension; and lying between 

 these lateral flaps is a more narrow, pointed, sharp, 

 pilose, submedial process divided posteriorly by a cleft. 



