ROBBER FLIES OF THE WORLD 



561 



tremely long, abundant and fine on the sides of the first 

 and second segments in both sexes and somewhat 

 shorter on the third segment. St«mites with abundant, 

 quite long, stiff, erect pile, the first sternite included. 

 Sides of first segment with 7 very long, rather slender 

 bristles in males only. Bristles absent on second and 

 third segments in both sexes. Fourth segment of male 

 with conspicuous, postmarginal fringe of 10 to 12 

 rather stout, backwardly curved, fringelike, black or 

 partly pale bristles. Fifth segment also with 10 to 12 

 similar, stout bristles. In the female the fourth seg- 

 ment has 4 weak, pale bristles ; fifth segment with 4 to 6 

 somewhat more stout, black bristles ; sixth segment with 

 6 long, moderately stout, black bristles; seventh seg- 

 ment with 3 bristles. Males with eight tergites; fe- 

 males with the eighth tergite extremely short and in- 

 corporated in ovipositor. In the males the eighth ter- 

 gite is two-thirds as long as the seventh; seventh 

 slightly shorter than the six; all others slightly and 

 progressively increased in length. Male terminalia 

 large, elongate, almost entirely consisting of the su- 

 perior forceps. Gonopod short. Female eighth tergite 

 extremely sliort, apically and obliquely truncate; the 

 eighth segment is somewhat compressed laterally; no 

 spines or spinous bristles present. Ninth tergite ex- 

 tremely short, the tenth only a little longer. 



Distribution: Neotropical: Stizolestes nigriventris 

 Philippi (1865). From the Chilean subregion. 



Genus Philonicus Loew 

 FiGUEES 774, 1514, 1523, 2263, 2328, 2491, 2495 



PhUonicus Loew, Linnaea Entomologica, vol. 4, p. 144, 1849. 

 Type of genus : Asilus albiceps Meigen, 1820, by monotypy. 



Philonotus Neuhaus, Diptera marchiea, p. 67, 1886. Type of 

 genus: Asilus albiceps Meigen, 1820, by monotypy. Un- 

 necessary change of name. 



Short, pilose, bristly flies of less than medium size 

 with cylindrical, tapered abdomen. They are charac- 

 terized by the moderately prominent, facial gibbosity, 

 the relatively narrow face, the shallowly excavated ver- 

 tex. Strong, long, dorsolateral bristles begin abruptly 

 at the wing level, but the scutellum has only 1 pair of 

 bristles. The end segment of the female terminalia 

 bears characteristic spines. Length 12 to 18 mm. 



Head, lateral aspect: The face on the upper half is 

 nearly plane with the eye or very slightly produced and 

 bears a moderately prominent, roimded and elevated 

 gibbosity below. Eye slightly recessive anteriorly be- 

 low. The occiput is thick and prominent throughout, 

 extending to the vertex ; occipital pile fine and scanty 

 above, becoming dense, long and copious below, with 

 curled ends ; bristles begin at the middle and consist of 

 15 stout but short and slightly curled elements. The 

 proboscis is short, slightly swollen towards the base, 

 stout and subcylindrical ; it has a high medial ridge, 

 the apex bears stiff pile curled forward. The base be- 

 low has a few, long, stiff hairs. Palpus of one segment, 

 rather stout subapically with relatively short, stiff pile. 



535914 — 62— pt. 2 10 



The antenna is attached at the upper third of the head 

 and the first two segments nearly equal in length. The 

 third segment is laterally compressed, slightly wider 

 than the second segment at the basal third; from this 

 point it tapers to the outer third and is then more 

 gently narrowed to the apex. The third segment is 

 equal to the combined length of the first two segments; 

 it bears a short microsegment and a thick style which 

 is very slightly longer than the third segment itself; 

 apex with a minute spine. The first antenna] segment 

 carries several stiff, appressed setae above and more 

 numerous setae below and 1 or 2 fine, long hairs. Second 

 segment with 5 or 6 stiff setae ventrally, fewer above ; 

 third segment with 1 or 2 minute setae dorsally. 



Head, anterior aspect: The face below the antenna 

 is less than one- fourth the head width and only slightly 

 divergent below; subepistomal area large, oblique, 

 nearly plane. The face is pubescent and bears num- 

 erous, prominent, rather long bristles on the middle of 

 the gibbosity. The upper bristles are directed straight 

 forward, the others curved obliquely downward; the 

 bristles are continued down along the sides of the sube- 

 pistoma. Front slightly divergent, the vertex slightly 

 convergent. Sides of the front with a few, weak 

 bristles. Vertex shallowly excavated with slanting 

 sides. Ocellarium moderately large with 4 short, curled 

 bristly hairs. Eye facets enlarged centrally. 



Thorax : The thorax is pollinose ; the pile of the meso- 

 notum is scanty but uniformly distributed and consists 

 of fine, suberect, basally stout setae. Acrostical ele- 

 ments present but poorly differentiated across the 

 middle of the mesonotum. Dorsocentral bristles differ- 

 entiated only across the wing level, where they become 

 abruptly long, stout, with 4 in each row. Humerus 

 with erect, fine pile. The lateral mesonotal bristles are 

 stout and long and consist of 2 notopleural, 1 supraalar, 

 1 suprapostalar, 2 postalar and 1 pair of scutellar 

 bristles. The scutellum is thick, convex, with im- 

 pressed rim and rather fine, scattered, erect pile. Pro- 

 pleuron with dense, long, tufted pile below and long 

 pile posteriorly; the ventral posterior section bears 3 

 slender bristles; pronotum with weak bristles. Meso- 

 pleuron dorsally with a band of very fine, erect pile, 

 posteriorly with only a few hairs. Upper steniopleuron 

 with a large patch of long, fine, erect pile ; pteropleuron 

 with a similar patch ; posthypopleuron with 1 to 3 stout 

 bristles and several long hairs. Metapleuron with a 

 fanlike vertical row of about 9 or 10 bristles, the lower 

 3 or 4 are stronger than the upper bristles; metanotal 

 slopes with long, fine pile; postmetacoxal area mem- 

 branous ; tegula pubescent only ; squama with a multiple 

 fringe. Prostemum widely fused laterally, only slight- 

 ly reduced posterolaterally. 



Legs : The hind femur and tibia are moderately elon- 

 gate and relatively slender. The anterior femur is 

 scarcely thickened toward the base ; all the femora and 

 tibiae are densely appressed setate on all surfaces. The 

 hind femur bears a pair of stout bristles dorsally at the 

 apex, 1 on each side, a similar pair subapically at the 



