ZENILLIA AND ALLIED GENERA— SELLERS 6 



2. Abdomen in both sexes wide and deep, almost globose ; fourth segment, unless 



contracted in drying, closing in a slit above genital opening (exclusive 



characteristics) 1. Zenillia (p. 4) 



Abdomen oj" ordinary form 3 



3. Front at vertex or narrowest part less than one-third width of head, rarely 



exceeding 30 percent of head width ; front narrower in male than in female, 

 with somewhat diverging margins; claws and pulvilli in male elon- 

 gated i 4 



Front at vertex or narrowest part more than one-third width of head, often 

 two-fifths of head width ; front more or less protruding, of equal breadth in 

 both sexes, with almost parallel or little diverging margins; claws and 

 pulvilli small in both sexes (exclusive characteristics) 6 



4. Scutellum with three pairs of marginal scutellars and an apical pair; bind 



tibia usually with unequal bristles, sometimes weakly ciliate in certain 



species 5 



Scutellum with four pairs of marginal scutellars and one strong decussate 

 apical pair (exclusive characteristic). Hind tibia strongly ciliate on 

 anterolateral side in both sexes; with regular, long, comblike, curved 

 bristles, among which one sometimes stands out larger. (Third abdominal 

 segment of male with dense patch of hairs underneath on each 

 side.) 5. Sisyropa (p. 97) 



5. Sternopleural machrochaetae two ; antenna with first two segments and 



basal part of third yellow ; frontal bristles descending to middle of second 

 antennal segment ; fourth segment of abdomen destitute of macrochaetae ; 

 thorax and abdomen wholly golden-pollinose 



8. Angustia, new genus (p. 107) 

 Sternopleural macrochaetae three or four ; antenna usually black, at most 

 first and second segments rufous ; frontal bristles descending at least to 

 base of third antennal segment ; fourth segment usually with either discal 

 or marginal macrochaetae ; species predominantly with thorax and abdomen 

 black, gray-pollinose 4. Aplomya (p. 70) 



6. Apical scutellars erect or proclinate, decussate ; four postsutural dorsocentral 



macrochaetae. Male without fronto-orbital bristles 7 



Apical scutellars curved backward, decussate; three postsutural dorsocentral 

 macrochaetae ; palpi yellow. Male with two fronto-orbital bristles 



6. Thelymyia (p. 103) 



7. Species predominantly gray-pollinose; palpi black 2. Phryxe (p. 31) 



Species predominantly golden-pollinose; palpi yellow 



7. Chrysophryxe, new genus (p. 10G) 



All the forms treated in this key will run to Zenillia in Curran's 

 key to the genera of Tachinidae. 9 



This key will eliminate the past practice that made it necessary to 

 cross reference some of the species in certain genera. The use of 

 sexual characters has been restricted. The primary characters cited 

 will place all individuals in their proper genus. Secondary sexual 

 characters have been used only as a supplementary assistance. 



8 Curran, C. H., The families and genera of North American Diptera, 512 pp., illus., 1934. 



