AUT. 9 TWO-WINGED FLIES OF TRIBE MILTOGRAMMINI ALLEN 95 



Genus GYMNOPROSOPA Townsend 



Gymnoprosopa Townsend, Trans. Amer. Ent. Soc, vol. 19, p. 108, 1892, 

 type, polita; Smithson. Misc. Coll., vol. 51, p. 64, 1908. — Coquillett, 

 U. S. Bur. Ent., Tech. Ser., No. 7, p. 128, 1897; Proc. U. S. Nat. Mus. 

 vol. 37, p. 548, 1910 (Hilarella). 



This genus also, has long been considered synonymous with Hila- 

 rella. Genotype specimens of Hilarella and Gymnoprosopa. posesss 

 rather striking differences in the conformation of the head and in 

 the distribution of pollen on the abdomen, which are linked with 

 certain minor variations, constant among the species of the respec- 

 tive groups, and should certainly be considered distinct genera. 

 From the more nearly related genus Eumacronychia, Gymnoprosopa 

 differs in having the male genitalia minute, not highly specialized, 

 in repose, largely concealed within the tip of the abdomen, while 

 the femnle genitalia are small and inconspicuous. These characters 

 associated with sinallness, the presence of three pairs of marginal 

 scutellar bristles of which the apical pair is at least as strong as the 

 extreme laterals, and the contour of the inner orbits which are not 

 more nearly approximated near base of antennae than at the vertex, 

 readily distinguish Gymnoprosopa from Eumacronycltia. Other char- 

 acters of the genus are as follows : 



Inner orbits not pinched in at level of vibrissae; frontal vitta light 

 red or yellow, at least as wide as the parafrontal; lunule scarcely 

 visible; a single frontal row of bristles terminating at base of anten- 

 nae, not suddenly divergent below; proclinate ocellar bristles present; 

 orbitals in both sexes ; antennae distinctly more than half as long as 

 the face: penultimate joint of arista short; vibrissae distinctly less 

 than length of second antennal joint above front edge of oral margin; 

 in profile, head length at vibrissae sometimes subec[ual, usually much 

 less than at base of antennae; lower part of bucca with sparse black 

 bristly hairs; no pale hairs about the oral cavity; proboscis moderately 

 stout, shorter than the head height, with fleshy labella and normal 

 palpi. Thorax with three strong postsutural dorsocentral bristles 

 and two sternopleurals. Pollen on intermediate segments of abdo- 

 men arranged in basal bands which are not scalloped or indented 

 on the apical margin ; abdomen never marked with large black spots. 

 Wing with the apical cell open; only the third vein bristly, last 

 section of fifth vein less than half the length of preceding section. 

 Joint of fore tarsus not ornamented, conspicuously reduced in size, 

 flattened, or otherwise modified from the normal in either sex; pul- 

 villi of male variable in length. 



None of the species of this genus are known to occur outside the 

 continental North American area, and I have as yet seen no speci- 

 mens from north of the continental United States. The genus is 



