428 



UNITED STATES NATIONAL MUSEUM BULLETIN 224 



The basitarsus has a distally produced denticulate 

 flange. Anterior basitarsus exceptionally elongate and 

 robust, longer than the remaining segment or the re- 

 maining basitarsus. Claws sharp, pulvillus and em- 

 podium well developed. 



Wings: The wings have an obscurely banded pat- 

 tern ; marginal cell widely open, anterior branch of the 

 third vein strongly sigmoid, ending well before whig 

 apex; posterior branch far behind. Fourth posterior 

 cell closed, remaining posterior cells widely open. 

 Anal cell closed and stalked ; alula large, ambient vein 

 complete. 



Abdomen : The abdomen is robust, as wide as the mes- 

 onotum and widest on the third to fifth tergites. Pile 

 short, scanty, erect and setate. Bristles absent. Male 

 with seven tergites, the eighth concealed. Females 

 likewise with seven tergites, the eighth forming a tri- 

 angular, convex ovipositor. Male terminalia conspicu- 

 ous, elongate, cylindrical, half rotate; the ninth seg- 

 ment is narrowly fused laterally and extended as a 

 large, extensive, undivided, shieldlike epandrium ; the 

 gonopods are apposed distally. The hypandrium is 

 widely cleft nearly to the base, the genital cavity open. 

 Ninth and tenth segments of the females short and cy- 

 lindrical. The eighth tergite and sternite are triangu- 

 lar, large, dorsoventrally depressed and shallowly con- 

 vex on both surfaces. 



Distribution : Neotropical : Pseudoryclus hicolor Bel- 

 lardi (1861) ; ruftventris Boeder (1887). 



Genus Pseudorus Walker 



Figures 235, 668, 1279, 1288, 2168 



Pseudorus Walker, Insecta saundersiana, vol. 1, pt. 2, p. 103, 

 1851. Type of genus: Pseudorus piceus Walker, 1851, by 

 monotypy. 



Easily recognized by the enormous, peaked, anteriorly 

 produced and humpbacked mesonotum. These are me- 

 dium size flies with the third antennal segment greatly 

 widened and angulate dorsally. The fourth posterior 

 cell is narrowly open or closed in the margin. Probos- 

 cis long and slender, extending a little beyond the an- 

 tenna and slightly compressed laterally. Length 17 

 mm. 



Head, lateral aspect : The face is moderately produced 

 on the upper two-thirds with a strong, ventral, liplike 

 extension abrupt dorsally, obliquely truncate below. 

 The eye is long, very distinctly wider on the lower half 

 and strongly convex. The posterior eye margin is plane 

 through the middle, convexly recessive below, more 

 gently above. Occiput not visible in profile. The pile 

 of the occiput consists of a single row of slender, bristly 

 hairs set deeply back from the eye margin. The pro- 

 boscis is directed horizontally forward and a little up- 

 ward ; it is slender and extends a little beyond the an- 

 tenna ; that portion which is beyond the face is nearly 

 as long as the head. It is a little compressed laterally ; 

 the apex is anterodorsally punctate and bears several, 

 stiff, bristly hairs above and below and with shorter pile 



continued ventrally nearly to the base. Palpus long 

 and slender, but not extended beyond the face; it is 

 cylindrical, with numerous, long, bristly hairs ventrally 

 and others at the apex which are a little more stiff. 

 There appears to be only one segment, with a trace of 

 a basal segment. Antenna attached near the upper 

 third of the head, the basal segments short and stout, 

 the first being a little longer than the second. The 

 third segment is quite large, somewhat thickened beyond 

 the middle and from the lateral aspect very broad across 

 the middle, and triangular dorsally, gently convex be- 

 low. It is nearly 3 times as wide as the first segment, 

 bluntly rounded apically and bears an apical pit with 

 short visible spine. First segment with 3 pairs of 

 bristly hairs ventrally, a stout bristle dorsolaterally, 

 and some setae. Second segment with 5 transverse 

 basal ventral bristles and from the base dorsally 1 quite 

 long, white bristle, longer than the first 2 antennal seg- 

 ments. Third segment orange brown. 



Head, anterior aspect : The face below the antenna is 

 not quite one-third the head width and the sizes are 

 parallel to the epistoma, slightly narrowed at the cheeks. 

 Face bare, except along the sides, which are densely 

 erect pubescent ; it is without pile except for a row of 

 5 or 6 pairs of slender, bristly hairs along the liplike 

 portion of the lower face. Subepistoma prominent, 

 gently oblique, and shallowly concave. The front is 

 rather large, wide, and is raised through the middle, 

 with 3 or 4 bristly hairs along the eye margin, which is 

 situated near the vertex, and 1 or 2 similar hairs lat- 

 erally in front of the ocelli. Vertex no wider than the 

 upper face, rather deeply excavated, the ocellarium unu- 

 sually large and prominent, the ocelli reduced and bear- 

 ing between the posterior ocelli 3 pairs of slender, 

 bristly hairs and 5 or 6 longer pairs behind. Anterior 

 eye facets moderately enlarged and flattened. 



Thorax : The thorax is everywhere vitreus and shin- 

 ing. The whole mesonotum is developed into a high, 

 obtuse, dorsally rounded, peaklike cone with the an- 

 terior portion steeper. Pile of mesonotum apparently 

 without acrostical elements but with some very delicate, 

 bristly pile laterally on the hump and on the whole of 

 its anterior overhanging surface ; it seems to correspond 

 to an irregular band of dorsocentral pile. In the type 

 of genus before me there is no pile posteriorly on the 

 mesonotum but it may have been denuded. Humerus 

 rather strongly protuberant, set off by almost rectan- 

 gular crease and bearing 3 or 4 fine hairs. The type 

 bears laterally 1 short, moderately stout, notopleural 

 bristle, apparently 1 or 2 postalar bristles, and possibly 

 1 or 2 supraalar bristles, now denuded. Scutellum ap- 

 parently without bristles ; it is rather thin but convex, 

 fused at the base, and lies rather flatly upon the exten- 

 sive metanotum. There are at least 3 or more pairs of 

 moderately developed, short, dorsocentral elements in 

 front of the suture. Propleuron with a few bristly 

 hairs ventrally and a narrow band of similar hairs on 

 the pronotum. Mesopleuron with a few bristly hairs 

 dorsally, 2 or 3 similar ones in the upper middle sterno- 

 pleuron. Metapleuron with a conspicuous, posterior 



