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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



Head, anterior aspect: The face below antenna is 

 about a fifth of head width and slightly divergent 

 below. Subepistomal area comparatively short, small 

 but oblique and encroaching but little on the face, nearly 

 plane and bare. The face is pubescent and bears a 

 number of conspicuous, long, slender, and sometimes 

 stout bristles on the lower and slightly elevated portion 

 of the face. These may consist of 8 to 10 bristles 

 ranged more or less as a narrow triangle with addi- 

 tional, shorter, fine bristles on the upper portion of 

 the face and with some stiff, long, scattered pile inter- 

 mixed. The antenna is attached at the upper fourth 

 of the head ; first two segments short, nearly equal in 

 length or the first a little longer. The third segment 

 is elongate, of the same width or sometimes wider than 

 the second segment; it is wide basally and tapers 

 mostly on the outer third until rather narrow at the 

 apex and it bears a long, bristly style which may be 

 more than half as long as the third segment; in addi- 

 tion, dorsally, at approximately the outer third, there 

 is an incision with a distinct, short spine. Pile of the 

 first segment composed of a few, short setae at the apex 

 above and below and ventrally with 1 to 2 long, stout- 

 bristles. Front short, pubescent, somewhat elevated 

 in the middle and with shallow, sublateral fossa; the 

 vertex is rather deeply excavated with prominent, high 

 ocellarium, bearing a pair of stout, long bristles. An- 

 terior eye facets strongly enlarged. 



Thorax: The thorax is thinly appressed pubescent; 

 the mesonotal pile is dense, bristly and rather strongly 

 appressed. Acrostical elements absent; dorsocentral 

 bristles weakly developed posteriorly. Humerus with 

 stiff, pile only; the lateral mesonotum has long, stout 

 bristles consisting of 1 posthumeral, 1 notopleural, 1 

 or 2 supraalar, 3 or 4 postalar, and 2 pairs of scutellar 

 bristles which may sometimes be exceptionally stout. 

 Scutellum rather thick, gently convex, pubescent with 

 numerous, appressed, bristly hairs and a deep basal 

 crease. Propleuron below with a number of fine, long 

 hairs; posterodorsal propleuron similarly pilose, the 

 pronotum has weak bristles. Posterior and anterior 

 sternopleuron with some scattered, long hairs; similar 

 fine, long hairs over much of the mesopleuron and 1 to 

 3 stout, long, mesopleural bristles. Hypopleuron pos- 

 teriorly with a number of fine, long hairs; metapleuron 

 with a wide band of extremely long, slender bristles, 

 the dorsal elements more stout. Metanotal slopes with 

 stout bristles and stiff pile; lateral and ventral meta- 

 sternum with long pile ; postmetacoxal area chitinized 

 and long; tegula with bristles; squamal fringe scanty 

 and composed of a single row. Prosternuni not 

 dissociated. 



Legs: The legs are stout without being swollen; the 

 dorsal femoral pile is appressed and setate but scanty, 

 the lateral pile suberect, quite scanty and longer. 

 There are 2 slender bristles dorsally near the apex and 

 a dorsomedial apical row of 5 or 6 stiff, bristly hairs ; 

 ventral margin with 15 to 20 slender, erect hairs and 

 ventrolaterally 10 to 12 longer, fine hairs with an addi- 

 tional, ventromedial, basal row of 4 or 5 quite long, 



slender hairs. Hind tibia with a moderately abun- 

 dant, nearly erect, long, ventral fringe and a brush of 

 setae in ranked pile only at the apical fifth ; the bristles 

 are quite long and tend to be basally stout and finely 

 attenuate ; they consist of 5 dorsal, 4 dorsolateral, 3 or 

 4 lateral, and 4 ventral ; basitarsus as long as the next 

 3 segments. Middle femur with a bristle anteriorly at 

 base and another at the distal third, but with only 

 bristly hairs dorsally and posterodorsally ; middle tibia 

 with exceptionally long, basally stout, attenuate 

 bristles, 4 anterodorsal and 4 anteroventral ; among the 

 former the distal elements are longer, among the latter 

 the basal elements are longer; the longer bristles may 

 be considerably more than half as long as this tibia; 

 the remaining bristles are 4 dorsal and 3 posterior 

 and 5 or 6 postero ventral bristles which are consider- 

 ably shorter and finer. Anterior femur with 5 or 6 

 long posterodorsal hairs and similar, finer, ventral 

 hairs; the posterior tibial bristles of which there are 



3 or 4 are quite long, but not as long nor as stout as 

 the medial, tibial bristles. Anterior tibia dorsally with 

 a double, dorsal row of 5 or 6 slender bristles. Tarsi 

 end in slender, sharp claws, curved chiefly at the apex, 

 well developed pulvilli and slender, bladelike empo- 

 dium not basally swollen. 



Wings : The marginal cell is closed with a long stalk ; 

 the anterior branch of the third vein is strongly arched 

 at the base, ending just before the wing apex ; posterior 

 branch ends far behind the apex. First posterior cell 

 narrowed to a fourth its maximum width; fourth 

 posterior cell closed with a short stalk ; end vein of the 

 discal cell and of the fourth posterior cell either in 

 strict alignment or slightly offset. Anal cell closed; 

 alula moderately wide, the ambient vein ends with the 

 second posterior cell ; the anterior crossvein enters the 

 discal cell near or before the basal third. 



Abdomen : The abdomen is as wide as the mesonotum, 

 with parallel or nearly parallel sides. It is gently 

 convex basally, strongly convex posteriorly with the 

 surface coarsely punctate, the sixth tergite tending to 

 be slightly cup-shaped. Sides of the first tergite with 



4 stout bristles; the second tergite laterally bears 2 or 

 3, the third tergite has 1 or 2 similar bristles. Abdom- 

 inal pile dense, appressed and setate, long and fine along 

 the lateral margins. The apex of the abdomen is not 

 as strongly curved downward as in Atoinosia Macquart, 

 even though the terminalia are also concealed in both 

 sexes. There are six tergites in the male with a narrow 

 lip of the seventh exposed ; seven tergites in the female, 

 the seventh is quite short, distinctly in evidence laterally 

 but not dorsally ; posterior margin of the sixth tergite 

 with a very slight emargination. Male terminalia small, 

 recessed and mostly concealed. The gonopod has a 

 narrow, transverse arm, which curves inward to meet 

 the corresponding element from the other side; in this 

 respect and in general they are similar to Atomosia 

 Macquart ; female terminalia form a minute, short, pro- 

 truded plate; the eighth sternite bears a circular medial 

 depression. 





