212 



UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



PAET 1 



ventral bristles, of which 2 at basal and apical third are 

 rather long and stout. Apex without spine. Basitarsus 

 nearly as long as the next three segments; tarsi end in 

 slender, sharp claws, well developed pulvilli, and a 

 short empodium, half as long as the claw and greatly 

 swollen on its basal half. 



Wings: The wings are hyaline, the marginal cell 

 widely open; the anterior branch of the third vein is 

 strongly arched backward to end at the apex of the 

 win"' which is also anteriorly arched backward. All 

 of the posterior cells widely open their maximum 

 width ; anterior crossvein enters the middle of the discal 

 cell; the upper end vein of the discal cell is a little 

 shorter than the lower vein; the middle end vein of the 

 second basal cell is long, the anal cell is closed with a 

 long stalk, the alula is quite narrow, not as wide as the 

 upper costal cell, the ambient vein complete. 



Abdomen : The abdomen is comparatively slender, a 

 little shorter than the total wing length and with nearly 

 parallel sides that tend to be thinned and a little curled. 

 Middles of the tergites somewhat flattened. Pile of 

 the abdomen short, exceptionally fine and suberect, but 

 the sides of the first and second tergites with some long, 

 fine pile. The first tergite has a vertical, posterior band 

 of 4 or 5 long, slender, bristly hairs. Males with seven 

 tergites and short liplike trace of the eighth which may 

 be concealed. In the female are eight tergites, the 

 eighth not pollinose, nearly or quite as long as the 

 seventh. Male epandrium completely divided and 

 separated ; proctiger quite small and short ; the gonopod 

 is well developed, becoming attenuate and sharply 

 pointed or hooked apically. Hypandrium very short, 

 almost concealed. Female terminalia with 4 pairs of un- 

 usually long and slender, apically rounded spines. The 

 ventral plate is thin, triangular, apically notched and 

 extending as a V-shaped scoop a little farther than the 

 eighth tergite. Accessory spines or bristles absent. 



Distribution: Ethiopian: Oligopogon ater Bigot 

 (1878) ; hyhotimis Loew (1847) ; nigripennis Engel and 

 Cuthbertson (1937) ; nitidus Efflatoun (1937) ; penicil- 

 ZaftwLoew (1857) ; poUinosm Engel (1932). 



Country unknown : fcarvUius Walker (1819). 



Genus Rhabdogaster Loew 



Figubes 08, 505, 1108, 1117, 1971 



Rhab dog aster Loew, Ofvers. Svenska. Vet.-Akad Forhandl., vol. 

 14, p. 346, 351, 1858. Type of genus: Rhabdogaster nudus 

 Loew, 185S, by monotypy. 



Very small, delicate, pale, pollinose flies with elon- 

 gate, subcylindrical abdomen, and readily distinguished 

 by the rather long, chitinized, postmetacoxal plate. 

 Length 7 to 8 mm. 



Head, lateral aspect : The face is plane with the eye 

 except for a minute, ventral portion exposed at the an- 

 terior margin of the epistoma, visible only because of the 

 posterior recession of the eye. The eye is rather longer 

 than average, quite convex anteriorly and posteriorly 

 as well, equally prominent above and below. The occi- 

 put is well developed and tumid, especially medially; 



it slopes rather abruptly down to the eye margin but 

 on the lower portion there is along the eye margin a 

 narrow, vertical rim which stands perpendicular to 

 the eye margin. Pile of the occiput fine and quite 

 scanty, moderately long ventrally and consisting of 

 only a few hairs, replaced on the upper half by 6 pairs 

 of slender, weak bristles. The proboscis is rather 

 long, distinctly compressed laterally but tapered near 

 the immediate apex to a bluntly rounded point which 

 bears 3 or 4 short, stiff hairs apically and as many 

 others ventrally on the apical third. The base has 

 3 or 4 fine, long hairs ventrally. There is a low dorso- 

 medial ridge and the base is very slightly swollen 

 ventrally and laterally. The proboscis is directed 

 obliquely forward and downward. Palpus distinctly of 

 two segments ; the first segment is short and excavated 

 with 3 or 4 long hairs ventrally. The second segment 

 is cylindrical, slightly tapered at base and apex, and 

 bears on all sides only a few bristly hairs which do not 

 quite extend to the apex. There is a minute, lateral, 

 subapical pore. 



The antenna is attached at the upper third of the 

 head, moderately elongate, distinctly slender; the first 

 segment is quite short, a little shorter than the second. 

 The third segment is slender and considerably more 

 narrow than the second segment; it is one and a half 

 times as long as the combined length of the first two 

 segments. This segment bears two microsegments, the 

 first is short but distinct, the second is two-thirds as 

 long as the third segment, attenuate apically with fine, 

 apical bristle and held obliquely downward. The first 

 antennal segment has several fine hairs ventrally and 

 shorter ones dorsally. Second segment with 1 to 2 mod- 

 erately long, stiff setae dorsally and 1 or 2 still longer, 

 stout setae ventrally. 



Head, anterior aspect : The face below antenna is a 

 fifth the head width and divergent below to nearly a 

 third the width. Subepistomal area prominent, deeply 

 concave, oblique and bare. The lateral creases along the 

 cheeks are deep and prominent. The face is pubescent, 

 with a narrow ventral row of weak, slender bristles 

 above the epistomal margin, 5 on each side. The front is 

 pubescent, very slightly widened toward the vertex, 

 without pile or bristles, the vertex with scarcely any ex- 

 cavation. The ocellarium is prominent, with vertical 

 sides and rather high ; it rises above the eye and bears a 

 few, minute hairs between the ocelli. Ocelli large and 

 protuberant and there are a few fine bristly hairs behind 

 the ocelli. Central eye facets greatly enlarged. 



Thorax : The thorax is densely short, appressed pu- 

 bescent. In lateral aspect the mesonotum is strongly 

 arched and convex both anteriorly and posteriorly. 

 The pile of the mesonotum is scanty, rather long, fine, 

 and bristly, with a well developed single row of acros- 

 tical elements separated by a rather wide apilose band ; 

 the dorsocentral elements are differentiated only op- 

 posite the suture, where they are weak and posteriorly 

 consist of 2 or 3 pairs of long, slender, bristly hairs. 

 Humerus pubescent only. The following complement 

 of bristles present laterally : 2 strong, rather long no- 



