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XJNITED STATES NATIONAL MUSEUM BULLETIN 224 



basitarsus is barely longer than the next segment. Hind 

 basitarsus as long as the next two segments. Postcoxa 

 with 3 bristles and other bristly hairs. All tarsi end in 

 stout, rather blunt claws which are only a little sharp- 

 ened, bent chiefly at the apex ; long spatulate pulvilli ; 

 and a short, bladelike empodium about half as long as 

 the claw, and swollen laterally. 



Wings: The wings are broad; the marginal cell is 

 closed with a long stalk, the subcostal cell quite narrow ; 

 the whig is not expanded although the costal cell ex- 

 tends beyond the subcosta. The second submarginal cell 

 is quite narrow throughout its length and long, origi- 

 nating at the end of the discal cell ; upper and lower 

 end veins of the distally widened discal cell of equal 

 length. Fourth posterior cell closed with a long stalk, 

 anteriorly convex. Anal cell closed and stalked ; second 

 basal cell ends in 3 veins, the middle vein long; alula 

 large, ambient vein complete ; the first to the third pos- 

 terior cells widely open. 



Abdomen: The abdomen is robust basally but not 

 quite as wide as the mesonotum. In the male the abdo- 

 men is subcylindrical, and scarcely at all tapered, being 

 robust and rather thick and wide posteriorly, but in the 

 female it is strongly tapered progressively, although 

 relatively wide as far as the end of the fifth segment. 

 Males with seven tergites only, the eighth apparently 

 completely eliminated or at most with a medial linear 

 membrane. Female with seven tergites, the eighth is 

 included in the ovipositor, a little longer than the 

 seventh; it is high basally, low apically and strongly 

 compressed laterally; the dorsal margin is narrowly 

 convex. Ninth tergite and the tenth minute and short ; 

 the abdomen is characteristically pollinose fasciate pos- 

 teriorly on the tergites, yellowish in females, greyish 

 white in males. Pile rather long and dense on the sides 

 of the first three tergites in both sexes and also con- 

 tinued moderately long in the female. The dorsal pile is 

 fine, suberect and a little shorter; bristles are absent ex- 

 cept on the first tergite, where they are very slender and 

 consist of 3 or 4 pairs. First sternite with short, fine 

 pile. Male terminalia unusually large and conspicuous, 

 not rotate; the superior forceps separated to the base, 

 longest ventrally and strongly sloping downward dor- 

 sally. Gonopod also large, convex ventrally; hypan- 

 drium extremely short, if present. 



Distribution: Palaearctic: Polyphonius laevigatus 

 Loew (1848). 



Genus Regasilus Curran 



FiGUEES 207, 685, 1406, 1415, 2200, 2209, 2421, 2422 



Regasilus Curran, Amer. Mus. Novitates, no. 487, p. 24, 1931. 

 Type of genus : Regasilus strigaria Curran, 1931, by original 

 designation. 



Eather small or medium size flies with the general 

 characteristics of Asikis Linne and like that genus 

 without bristles on the sides of the abdomen except on 

 first tergite. Metanotal callosity without pile or 

 bristles. It differs in the absence of bristles or pile 



upon the metanotal callosity. It has well developed 

 acrostical and doreocentral bristles anteriorly which 

 separate it from Apoclea Macquart. Hind femur with 

 14- to 16 stout, ventral bristles in a partly double row. 

 There is a strong gibbosity on the lower half of the face 

 which distinguishes it sharply from the Neolophonotits 

 Engel group. Length 14 to 18 mm. 



Head, lateral aspect : The head is of medium length, 

 the face nearly but not quite plane with the eye on 

 the upper half but with an extensive gibbosity on the 

 lower half which tends to be rather abruptly developed 

 dorsally. The occiput is short on the upper half of the 

 head, a little more promment at the top of the eye 

 and still more so on the lower third, where the eye is 

 posteroventrally recessive. The lower third of the 

 occiput bears rather fine pile ; weak bristles are found 

 over the middle of the occiput and are strongly turned 

 downward; near the upper eye corner are 6 stout 

 bristles, some of them strongly proclinate. The pro- 

 boscis is rather small, cylindrical, and slightly widened 

 towards the base, with a blimtly rounded apex. It ex- 

 tends only a short distance beyond the face and bears 

 much, coarse, long pile ventrally on the basal half. 

 Palpus small, cylindrical, of one segment, with fine ter- 

 minal hairs. The antenna attached to the upper third 

 of the head; the first segment is twice as long as the 

 second and bears ventrally and laterally unusually nu- 

 merous, moderately oblique bristles. Second segment 

 with 2 or 3 fine setae subapically, above and below. 

 Third segment missing from the material available. 



Head, anterior aspect: The head is about 1% times 

 as wide as high. The face below the antenna is about 

 a fifth the head width, or less, and strongly divergent 

 below. Surface of face and the rather short cheeks 

 pubescent. Pile absent on the plane portion of the face. 

 The gibbosity is densely beset with long, slender, 

 slightly curved bristles. Placed on a small, medial, tri- 

 angular area just before the epistoma are about 6 re- 

 markably stout bristles. More slender bristles are con- 

 tinued along the whole border of the large, oblique, sub- 

 epistomal area. The front is short, wider tlian the 

 upper face, with a subocular row of 3 or 4 quite fine, 

 bristly hairs continued on to the vertex, and adjacent to 

 it medially is a row of 4 other hairs. The vertex is 

 distinctly narrowed, moderately excavated, and more 

 deeply excavated behind. The ocellarium is medium in 

 size and set anteriorly forward and has vertical sides. 

 There are 4 pairs of long, slender, bristly hairs between 

 the ocelli and 2 pairs beliind. 



Thorax : The mesonotum is high and strongly arched 

 both anteriorly and posteriorly. The anterior portion 

 tends to be a little narrowed and pinched or compressed 

 sublaterally. The surface is thinly pollinose, with a 

 broad band and submedial stripe of more dense, pale 

 pollen. Thei'e is a submedial, extensive, bare area. 

 The pile is scanty and scattered but long and bristly in 

 character. There is a distinct, double row of rather 

 long, acrostical elements and dorsocentral elements are 

 differentiated by length at a plane corresponding to the 



