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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



ment is swollen ventroapically and bears 5 to 6 stout, 

 long bristles, some long, dorsal setae, together with 

 some shorter, bristly, ventrolateral pile; second segment 

 with only short, lateral and dorsal setae. 



Head, anterior aspect: Face below antenna is one- 

 third the head width and slightly divergent below. 

 Subepistomal area comparatively small, oblique, con- 

 cave and bare. The face is quite densely covered with 

 long, slender bristles and bristly pile, but the lateral 

 margins are narrowly apilose. These face bristles are 

 a little shorter beneath the antenna; most of them are 

 slightly curved and extend obliquely downward. The 

 front and vertex are no wider than the lower face. 

 Front with numerous, long, bristly hairs along the eye 

 margins and a few other subappressed, shorter hairs 

 on the lateral third. The front is short, nearly hori- 

 zontal, pollinose and slightly depressed. Vertex almost 

 completely without excavation, the ocellarium is low, 

 wide, with large ocelli and numerous bristly hairs 

 across the middle. It extends a little above the eyes in 

 profile. Anterior eye facets only a little enlarged. 



Thorax : The thorax is minutely appressed pubescent 

 on the pleuron and laterally on the mesonotum; re- 

 mainder of the mesonotum is subpollinose and opaque. 

 Pile of the mesonotum unusually abundant, long, stiff 

 and erect with similar long pile on the humerus and 

 with a laterally directed extensive tuft behind the hu- 

 merus. The following complement of bristles is pres- 

 ent : 3 notopleural, 3 or 4 supraalar, 3 postalar and a 

 wide band of slender bristles in several rows on the 

 scutellar margin. Disc of scutellum with equally long, 

 bristly pile. Propleuron with abundant, long, slender, 

 bristly pile laterally and upon the anterior collar where 

 weak bristles are also present. The anterior and upper 

 middle stemopleuron both have a tuft of long, stiff 

 hairs. Upper and posterior border of the mesopleuron 

 with numerous, long, stiff, bristly hairs. Pteropleuron 

 and hypopleuron apilose. Upper pteropleuron some- 

 times with 3 or 4 slender bristles. Metapleuron with a 

 vertical band of numerous, long, slender bristles and 

 bristly hairs or with a single row containing 10 ele- 

 ments. Lateral slopes of the metanotum micropubes- 

 cent only. Lateral metasternum with a few long hairs 

 at its posterior border; ventral metasternum with nu- 

 merous, long hairs, chitinized and separated posteriorly 

 by membrane. Postmetacoxal area membranous; teg- 

 ula with 3 or 4 long setae; anterior basalare with a 

 conspicuous tuft of 12 or more long, bristly hairs. 



Legs : All the femora are stout, at most only slightly 

 swollen; the anterior femur is shorter or proportion- 

 ately wider, the hind femur slightly narrowed towards 

 the base ; all femora densely long, appressed setate ante- 

 riorly and dorsally and with somewhat less abundant, 

 short, subappressed pile ventrally. This pile on the 

 first four femora tends to become longer on the basal 

 half. Tibia also densely appressed setate; medial sur- 

 face of the hind tibia and anterior tibia with a brush 

 of setae. The following complement of moderately 

 long, strong bristles present : on the hind femur 7 ven- 

 trolateral with 4 shorter bristles at the base; 5 lateral, 



2 subapical dorsolateral, 1 similar dorsomedial bristle; 

 the apex has on the upper half a circlet of 8 weaker 

 bristles; the ventral surface has 5 or 6 long, bristly 

 hairs progressively lengthened towards the base and the 

 basal ones doubled. Hind tibia with 4 dorsomedial, 

 5 dorsolateral, and 3 ventrolateral bristles and the apex 

 with 8 bristles. Hind basitarsus stout, longer than 

 the next three segments. Middle femur with 1 poste- 

 rior subapical, 1 or 2 posterodorsal subapical bristles, 

 and 5 or 6 ventral bristly hairs. Middle tibia with 

 short bristles which are weak with 4 anterodorsal, 5 

 posterodorsal, 7 posterior, and 3 or 4 posteroventral 

 bristles. Anterior femur with 2 slender bristles poste- 

 riorly on the outer half; this tibia has the bristles re- 

 duced and weak. There are 4 or 5 short anterodorsal, 

 2 or 3 posterodorsal, and 6 posteroventral bristles. 

 Apex without spine. All tarsi end in short, sharp 

 claws, strongly bent at the apex, well developed pul- 

 villi and comparatively short empodium, which is 

 slightly compressed and a little thicker at the base. 



Wings: The marginal cell, all of the posterior cells 

 and anal cell open. The anal cell is narrow and the 

 fourth posterior cell is narrowed to not more than one- 

 third its maximal width. The anterior crossvein 

 enters the discal cell at or just before the middle. The 

 second basal cell ends in 3 veins, the middle one short. 

 Alula no wider than the costal cell; ambient vein com- 

 plete; wings hyaline, approximately as long as the 

 abdomen. 



Abdomen: The abdomen is not quite as wide at its 

 base as the mesonotum, but with an appearance of 

 robustness accentuated by long, dense pile. Abdomen 

 somewhat cylindrical and with a tendency to be com- 

 pressed laterally. Male with eight tergites, the eighth 

 extremely short, one-sixth as long as the seventh and the 

 seventh tergite at most two-thirds as long as the sixth. 

 Female with eight tergites; the last two lack pollen or 

 sometimes only the eighth lacks pollen. Eighth seg- 

 ment of the female quite short, one-fourth as long as 

 the seventh, the seventh one-half as long as the sixth. 

 The abdomen tends to be opaque and dark in color, 

 probably from pollen, with in some species sharp, 

 posterior bands of pale colored pollen. Bristles absent 

 or the sides of the first tergite may have 10 or 12 slender, 

 bristly hairs. Pile long, bushy and rather dense in 

 females, becoming shorter to the end of the fifth tergite 

 and very short beyond. The long pile is continued in 

 the male on to the last tergite. First sternite without 

 pile. Male terminalia short, rotate one-fourth to the 

 right ; epandrium short, with a deep, very broad sulcus 

 reaching virtually to the base, so that laterally on each 

 side the epandrium is produced into moderately large, 

 narrowed obtuse lobes. Hypandrium very short and 

 undivided. Gonopod basally enlarged, convex and 

 swollen, with sharply pointed apical process. Female 

 terminalia quite short and with a row of stout spines 

 on each side, which are rather deeply recessed in the 

 eighth tergite. The ventral plate is compressed into a 

 triangular, deep, scooplike process. 



