412 



UNITED STATES NATIONAL MUSEUM BULLETIN 224 



tensive, triangularly produced until it is a fifth the 

 length of the sixth tergite. 



Distribution: Oceania: Despotiscus simmondsi Bezzi 

 (1928). From Fiji. 



Genus Chymedax Hull 



Figuses 288, 679, 1274, 1283 



fltitniola.r- Hull, Ent News, vol. 69, p. 99, 1958. Type of 

 genus: Chymedax delicatulus Hull. 1958. 



Minute, slender, black asilids belonging to the sub- 

 family Laphriinae. Characterized by the presence of 

 only 4 posterior cells and of 7 abdominal segments in 

 males. Marginal cell closed and stalked. Third an- 

 tennal segment with a small microsegment at apex, 

 more slender than the third segment, and above it, 

 arising from the third segment a small, bristlelike spine. 

 Length 6.5 mm. 



Head, lateral aspect : The head is comparatively long, 

 and quite convex anteriorly. Face visible in profile 

 only slightly below. Occiput developed only submedi- 

 ally and only in the middle of the head. Proboscis 

 quite small, short and cylindrical. Palpus reduced to 

 a minute stub with a few, fine, subapical hairs. The 

 antenna is slender and longer than the head, attached 

 at the upper third of the head. The first segment is 

 especially slender, twice as long as the wider, beadlike 

 third segment, Third segment, microsegment in- 

 cluded, not quite twice the combined length of the 

 first segments. It is slender throughout and at the 

 apex bears a short, distinct microsegment of more nar- 

 row proportions and above it, arising from the third 

 segment, a bristlelike spine. 



Head, anterior aspect: The face about, a twelfth the 

 head width, with parallel sides. It is micropubescent, 

 but the subepistoma and cheeks are shining; subepis- 

 tomal fossa linear from encroachment of anterior cheek 

 area. Face without pile and bristles restricted to 2 

 pairs, one above the other, situated on the lowest part 

 of face and consisting of long, slender elements. Front 

 wider than face, the vertex narrowed and slightly ex- 

 cavated. The ocellarium is comparatively low but has 

 vertical sides and lacks bristles or hairs. Anterior eye 

 facets considerably enlarged. 



Thorax: The thorax is short with the mesonotum 

 low. Pile of mesonotum abundant, consisting of undif- 

 ferentiated, subappressed, fine but stiff, yellowish setae. 

 There is 1 fine, slender, bristly hair on the notopleuron, 

 1 above the wing, none on postalar callosity or scutel- 

 lar margin. Presternum not dissociated. Postmeta- 

 coxal area of metasternum with a strong, chitinized 

 arch. Metanotal callosity with a patch of bristles. 



Legs: The hind femur moderately elongate and a 

 little swollen on the outer half but with the lower mar- 

 gin plane. Ventrolateral margin with several long, 

 slender, bristly hairs. Posterior tibia with 2 quite long, 

 conspicuous, attenuate bristles laterally. Middle tibia 

 with a long, slender, anterior bristle at the basal third, 

 another at the outer third also with an equally long 



but stouter ventral bristle located at the middle and 

 again at the basal fourth. Anterior tibia with several 

 long, slender, bristly hairs and all the tibiae with 

 shorter, fine pile. The basitarsi of the front and middle 

 legs have very long, apical bristles and long, postero- 

 basal bristles; hind basitarsus with 2 quite long, an- 

 terior bristles, 1 at base, 1 at apex. Claws slender; 

 pulvilli short, but broad and well developed. 



Wings : The wings are villose throughout. Marginal 

 cell closed and stalked. Only four posterior cells pres- 

 ent, the third wanting. Anal cell closed and stalked. 



Abdomen: The abdomen is elongate and slender, the 

 upper surface gently convex. The abdomen is shallowly 

 punctulate, the pile fine and setate; a few, fine bristles 

 are present on the sides of only the first and second 

 tergites. Seven segments are present in the male. The 

 seventh segment is a little less than half the length of 

 the sixth and directed downward at an angle of 45 

 degrees; it encloses the small male terminalia below, 

 which appear to be rather similar to those of Atomosia 

 Macquart. 



Distribution: Oceania: Chymedax delicatulus Hull 

 ( 1958) . From the Solomon Islands. 



Genus Cenochromyia Hermann 



Figures 241, 655, 1328, 1337, 2117 



Cenochromyia Hermann, Nova Acta Acad. Caes. Leop.-Carol., 

 vol. 96, p. 115, 1912. Type of genus: Cenochromyia xan- 

 thogaster Hermann, 1912, by original designation. 



Rather small flies characterized by the membranous, 

 postcoxal region; yellow or yellow and black colora- 

 tion with all the pile and bristles pale yellow and 

 the wings often banded. The male terminalia is prom- 

 inent but not rotate or only slightly so. Tergal 

 bristles are poorly or not at all differentiated. The 

 face varies but is unusually quite narrow and narrowed 

 in the middle. The proboscis is short and more or less 

 cylindrical. The hind claws are characteristically 

 arched and hooklike. Length 8 to 12 mm. 



Head, lateral aspect : The face is short, a little more 

 prominent below due to the recession of the eyes but 

 otherwise nearly plane in profile. The eye is distinctly 

 narrowed ventrally and is also strongly anteroventrally 

 recessive, beginning at a level corresponding to the 

 upper third. It is gently convex posteriorly and 

 strongly convex in front. The occiput is a little thick- 

 ened medially on the middle and lower portion but re- 

 cedes above, leaving the upper comers of the eye 

 broadly rounded. Pile of occiput abundant, short and 

 stiff ventrally, replaced in the middle and above by 

 stiff, rather short bristles set a considerable distance 

 from the eye margin and with some short, bristly pile 

 lying between them and the eye margin. Behind the 

 vertex on the sloping sides are 3 long, rather conspicu- 

 ous bristles strongly curved medially at their tips. All 

 pile and bristles of the entire insect in the 2 species 

 before me are yellow, except for a little dark brown 

 pile on the mesonotum and sometimes on the antenna. 



