LEPTOOASTBINAB 



ROBBER FLIES OF THE WORLD 



317 



fifth posterior cell is present, as well as the first pos- 

 terior cell. Therefore, it may be considered that 3 pos- 

 terior cells are present, the second, third, and fourth 

 and discal forming a single cell. Seventh vein absent. 

 Only what would constitute the anal cell is narrow and 

 attenuate lying along the basal posterior margin; first 

 and second basal cell complete and large. Ambient 

 vein complete, with a long, fine fringe, the hairs of 

 alternating length. The whole wing is rather densely 

 villose. 



Abdomen: The abdomen is exceptionally long and 

 slender, not quite twice as long as each wing. The 

 second segment is more than half as long as a wing, 

 no thicker than the distal portion of the hind tibia 

 and cylindrical. The first segment is apparently very 

 short and more or less fused with the second. Third 

 and fourth segments no wider than the second, their 

 combined length about the same as the second. Female 

 with eight tergites, the sixth and seventh are long and 

 swollen and the abdomen as a result is clavate. The 

 eighth segment is about a fifth as long as the seventh. 

 Female terminalia is small and quite inconspicuous. 

 Pile of the abdomen is short, fine and setate, rather 

 abundant except on the second tergite where it is scanty 

 and stout. No males were seen. 



Distribution: Neotropical: Eurhabdus zephyreus 

 Aldrich (1923). 



An undescribed species is found in Jamaica, accord- 

 ing to a communication from Dr. Thomas Farr. 



Genus Dolichoscius Janssens 



Figures 1S9, 605, 1176, 1184, 1585, 2053 



Dolichoscius Janssens, Bull. Inst. Sei. Nat. Belgique, vol. 28, 

 p. 9, 1952. Type of genus : Dolichoscius francoisi Janssens, 

 1952, by monotypy. 



Flies of medium size, which like Lasiocnemus Loew 

 and Ophionomima Enderlein have dense, conspicuous 

 brushes of pile on part of the hind legs. In Dolicho- 

 scius this pile is restricted to the distal half of the hind 

 tibia and the first tarsal segment and progressively de- 

 creasing on the remaining segments. In Ophionomima 

 the conspicuous brush of pile is found on the whole 

 dorsal surface and distal half of the lateral and ventral 

 surfaces of the femur, not of the tibia. In Lasiocne- 

 mus, to which this genus is probably more closely re- 

 lated, the long, dense, erect pile is present on almost 

 the whole of femora and the tibiae and also its 

 tibia begins to be swollen at the base. Basal half of 

 wing in Dolichoscius greatly and gradually narrowed. 

 Length 13 mm. 



Head, lateral aspect : The head is of moderate length, 

 the profile convex both posteriorly and anteriorly. 

 The occiput is swollen gradually and most extensive 

 just above the middle. Occiput with abundant, long, 

 fine, delicate pile. The eye is considerably narrowed 

 dorsally. The ocellar tubercle and ocelli are visible 

 in profile. Face quite short and visible only below 

 as a small triangular extension. The proboscis is short 



but exceptionally stout and high and very little com- 

 pressed; it has a short, basal and dorsal thin ridge 

 or extension. Apex bluntly rounded and attenuate. 

 Palpus short, of 1 segment, cylindrical, with a few 

 short hairs and some pubescence at the apex. The 

 antenna is attached close to the top of the head ; the 

 front is therefore quite short. 



Head, anterior aspect: The epistomal margin bears 

 a single row of long, fine, matted, stiffened hairs which 

 are not as long as the proboscis and are broken up 

 into 3 parts containing approximately 12 elements. 

 Remainder of face without pile; the face is quite nar- 

 row, strongly divergent below and approximately a 

 twelfth the width of the head across the middle. Ante- 

 rior eye facets strongly enlarged. Vertex with almost 

 no excavation ; the ocellar protuberance is low with the 

 large ocelli laterally protuberant. 



Thorax: The mesonotum with a narrow band of 

 acrostical pile anteriorly; the sides of the mesonotum 

 bear numerous, fine, long, erect hairs. The mesonotum 

 is rather high and convex and anteriorly abrupt. 

 Notopleuron with fine, long pile; bristles absent except 

 for 1 notopleural, 1 supraalar. There are no postalar 

 and no scutellar bristles. The scutellum is quite small, 

 short, flattened, pubescent, margined with a band of 

 copious, rather long, fine, erect pile. The transverse 

 suture and the wing are placed far to the rear of the 

 thorax ; nearly five-sevenths of the thorax lies anterior 

 to the suture. Mesopleuron with a dorsal band of 

 long, fine pile. Hypopleuron pubescent but not pilose. 

 Metapleuron micropubescent only except for 2 fine 

 hairs immediately in front of the halteres. Anterior 

 mesopleuron with a long, downward turned mat of 

 pile. Stalk of the halteres quite long. 



Legs: The hind femur extremely long and slender 

 and strongly thickened on the outer two-fifths where 

 it is nearly three times as wide as the middle and 

 base. The pile is rather short and appressed but sub- 

 erect ventrally. There is a pair of weak bristles dor- 

 sally at the apex. Hind tibia equally long, quite slen- 

 der on the basal half, but considerablj- thickened and 

 expanded apically, and bearing a dense, long brush 

 of long, black, oblique pile, which is longest dorsally 

 and dorsolaterally but continues over the ventral dor- 

 sal surface as shorter pile. The apex bears 1 lateral 

 and 2 very long, ventral, spinous bristles; in addition 

 there is 1 medial apical bristle which is pale. Hind tar- 

 sus also ornamented with special pile ; the dorsal pile is 

 nearly erect, quite long on the basitarsus and pro- 

 gressively shorter on the remaining segments. Last 

 tarsal segment long and cylindrical and nearty twice 

 as long as the preceding segment. Middle femur is 

 short, slightly arched and bears short pile and 2 weak 

 bristles apically and posterodorsally. The posterior 

 pile is somewhat longer especially down the middle of 

 this femur. Middle tibia with a posteroventral row of 

 5 quite long, oblique, white bristles; the apex has 1 

 ventral, 1 anterior, 1 posterior, 1 medial bristle. Ante- 

 rior femur scarcely more than two-thirds the length of 

 the middle femur; it is very short pilose with a weak 



