82 



ROBBER FLIES OF THE WORLD 



Head, anterior aspect: The face below antenna one- 

 fourth of head width, and divergent below. The sub- 

 epistomal area is moderately large, slightly oblique. 

 Face thinly pubescent, with 8 or 10 short hairs on the 

 plane upper portion; the gibbosity is thickly covered 

 with numerous, quite long and slender bristles, con- 

 tinued down the sides on the upper half of the epistoma. 

 Front micropubescnt with a marginal row of long, 

 slender bristles; vertex deeply excavated, with oblique 

 sides ; the ocellarium high and prominent and bearing a 

 pair of rather stout, long, divergent bristles between the 

 ocelli ; and behind with 2 or 3 pairs of short pale hairs. 

 Anterior eye facets strongly enlarged. 



Thorax: The pleuron everywhere minutely micro- 

 pubescent, the mesonotum shining, with pubescence 

 only adjacent to the humerus medially and below the 

 postcallosity. Pile of mesonotum dense, quite short, 

 curled, flat appressed, setate and brassy, with a few, 

 fine, long, bristly dorsocentral hairs on the anterior 

 half but only 1 or 2 posteriorly. Acrostical bristles 

 not differentiated. The following complement of lat- 

 eral bristles present: no humeral bristles, the humeri 

 without the conspicuous tuft of weak bristles in Apoxy- 

 ria Schiner ; 2 notopleural, 1 of these much the weaker; 

 1 supraalar; 1 postalar; and 1 pair of scutellar bristles ; 

 all these are weak, slender and long. Scutellum mod- 

 erately thick and convex, with abundant, appressed, 

 brassy, curled pile basally. Prothorax with abundant, 

 long, fine pile ventrally and similar pile on the collar 

 and posteriorly; bristles absent. Anterior sterno- 

 pleuron and the upper posterior sternopleuron with a 

 tuft of coarse pile. Upper and posterior mesopleuron 

 with numerous, appressed, long, coarse hairs; post- 

 hypopleuron with many, fine, erect hairs; pteropleuron 

 apilose; metapleuron convex with a vertical band of 

 long, fine pile or bristly hairs. Lateral slopes of the 

 metanotum strongly convex and bullose but separated 

 from the medial portion only by a shallow depression 

 without pile. Lateral slopes of the metasternum with 

 abundant pile. Ventral metasternum wide, chitinized, 

 with numerous, long, fine, erect hairs; postmetacoxal 

 area short and membranous. 



Legs: Hind femur a little swollen, beginning near 

 the base and reaching the maximum width before the 

 middle; the lower surface is not quite plane. Hind 

 tibia stout, and a little swollen, beginning at the base. 

 Dorsal pile of all the femora short, appressed and setate, 

 ventral surface of the hind femur with a dense fringe of 

 fine, erect pile beginning in the middle and extending 

 over the ventromedial aspect ; hind tibia with a similar 

 ventral fringe; appressed setae confined to the medial 

 surface. Dorsal margin of the hind femur with 4 to 

 6 fine, long, bristly hairs; this tibia has moderately 

 stout bristles, 2 lateral at the middle and just beyond 

 the middle, 2 dorsolateral beyond the middle, and 5 

 short, slender dorsomedial bristles. The hind basitar- 

 sus as long as the next three segments and much less 

 robust than in Apoxyria. Middle femur with a weak 

 anterodorsal bristle at the outer fourth; this tibia with 

 prominent bristles, 3 long, stout anterodorsal, 5 or 6 



short posterodorsal, 4 ventral, and 2 anteroventral. 

 Anterior femur with a true dorsal row of 4 fine bristles 

 on the outer half; its tibia has 5 or 6 short anterodorsal 

 bristles; 8 posterodorsal, 3 or 4 long posteroventral 

 bristles, and 5 or 6 slender, ventral, bristly hairs. Apex 

 without spine. All tarsi end in sharp claws, long pul- 

 villi and long, bladelike, not swollen empodium. 



Wings: The wings are broad, marginal cell open 

 though greatly narrowed ; the apex wide and convex, the 

 vein ending at a right angle; anterior branch of the 

 third vein strongly sigmoid, ending above the apex of 

 the wing, posterior branch ending well behind the apex ; 

 base of second submarginal cell very strongly swollen 

 aneriorly at the base. First posterior cell open but nar- 

 rowed; fourth posterior and anal cells closed but 

 stalked. Alula short; ambient vein complete. 



Abdomen : The abdomen is as wide as the thorax ; six 

 tergites in the male ; eight tergites in the female, but the 

 seventh and eighth greatly reduced and very short; 

 the eighth is three-fourths as long as the seventh, but 

 seventh is only about one-fifth as long as the sixth. 

 Pile of abdomen moderately long, abundant and stiff 

 on the sides of the first tergite ; bristles absent. There 

 are a few, fine, long hairs on the extreme, lateral mar- 

 gins of the second tergite, becoming fewer and shorter 

 on the remaining tergites ; the greater part of the pile 

 on all the tergites is short, flat appressed, and brassy. 

 Female terminalia very short and inconspicuous, pro- 

 truding a short distance beyond the eighth tergite, the 

 ninth nearly as long as the eighth but the tenth tergite 

 minute. The first tergite is nearly three- fourths as long 

 as the second, the first sternite appears to be absent or 

 greatly reduced, the second bears considerable long pile 

 and is considerably shorter than the corresponding ter- 

 gite. Third sternite and fourth are also considerably 

 shorter but the fourth and fifth appear to end with their 

 corresponding tergites. A female from the Hermann 

 collection was studied; males of two new species have 

 been seen. 



Distribution: Neotropical: Helolaphyctis americana 

 Carrera (1955) ; modes ta Hermann (1920). 



Genus Hexameritia Speiser 



Figures 32, 420, 425, 862, 871, 1994 



Eutrichodes Hermann, Zool. Jahrb. vol. 43, p. 190, 1920. Pre- 

 occupied. Type of genus: Dusi/pecus micans Philippi, 

 1865, by original designation. 



Hexameritia Speiser, Zool. Jahrb., vol. 43, p. 447, 1920. Change 

 of name. 



Small flies readily recognized by the dense, rather 

 wholly pilose appearance of the head, thorax and legs 

 and the lateral margins of the abdomen. Moreover, 

 the lower half of the face is rounded and a little pro- 

 tuberant, densely beset with fine bristles or bristly pile, 

 the proboscis is short and truncate, the abdomen ex- 

 ceptionally wide, flattened and shining. Length 10 to 

 12 mm. 





