46 



UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



Legs: Femora and tibiae stout, without being swol- 

 len. The pile is dense, matted and brushlike on all 

 sides. The bristles are obscured by the density of the 

 pile. The f ollowing complement of very stout, moder- 

 ately long bristles is present: hind femur with 3 or 4 

 dorsolateral, 2 subapical dorsal, 1 subapical dorso- 

 medial, and on the ventrolateral margin 8 which 

 extend back to the basal third, at which point is a 

 cluster of some 6 or 8. The hind tibia bear 5 or 6 

 dorsolateral, 2 dorsomedial at the middle and beyond, 

 2 lateral and distal, and 5 ventral bristles confined to 

 the outer half. Middle femur with a loose cluster of 7 

 anterodorsal bristles just beyond the middle, also 2 

 posteroapical ones. Midtibiae with 2 or 3 dorsal 

 bristles, 1 posterior and 1 anterior near the middle, be- 

 sides 1 or 2 at the outer third. No apical spur present 

 at apex of midtibia in either sex. The anterior femur 

 has a conspicuous, long cluster of subappressed, stout 

 bristles ventrally at the base with at least 10 elements. 

 Anterior tibia bears 7 or 8 dorsal bristles, 5 or 6 slender 

 posterior bristles; a medial tibial brush of dense setae 

 is restricted to the anterior pair, absent on the hind 

 pair; anterior tibial apex without spine. All tarsi 

 short; the pulvillus well developed; the empodium 

 long, slender and somewhat bladelike, the claws stout 

 and sharp. 



Wings : The wings pointed apically, unusually broad 

 basally. Marginal cell open but narrowed to two- 

 thirds its greatest width. The anterior branch of the 

 third vein ends well above the wing apex and is ap- 

 pendiculate at its base. The first posterior cell is 

 widely open, the fourth closed and stalked, the vein 

 ending this cell and the lower end vein of the discal 

 cell are drawn out along the wing margin in a nearly 

 straight line. The anal cell is closed with a long stalk; 

 middle end vein of the second basal cell very short or 

 absent; alula large, ambient vein complete. 



Abdomen: The abdomen is robust, as wide as the 

 mesonotum, the apparent width greatly increased by 

 the extraordinarily dense, long, matted, lateral pile, 

 which becomes equally dense but shorter across the 

 middle of all the tergites except the first. Sides of the 

 first tergite with coarse, long pile only. Male with 7 

 tergites and in addition a very narrow, liplike ex- 

 posure of the eighth tergite. Female with 6 tergites, 

 the seventh and eighth incorporated into the narrow 

 subtriangular ovipositor, the eighth being strongly 

 compressed dorsoventrally. Apex still more narrow. 

 Male terminalia moderately large and conspicuous, but 

 distinctly shortened, obtuse, subtruncate, exposing in- 

 ternal structures. These terminalia are directed up- 

 ward and not rotate. The superior forceps comprise 

 nearly the upper half; the hypandrium forms an arch- 

 ing, lateral hemicylinder, meeting the superior for- 

 ceps; if gonopods are present they are completely en- 

 closed. I have studied a series, but have not had speci- 

 mens to dissect. Wings in the female reach to the 

 end of the ovipositor and in the male are considerably 

 longer than the abdomen. 



Distribution: Neotropical: Obelophorus landbecki 

 Philippi (1865); terebratus Macquart (18-49). Both 

 species from the Chilean subregion. 



Genus Psilozona Ricardo 



Figures 46, 402, 840, 849, 1635, 1890, 1891, 1907 



Psilozona Ricardo, Ann. Mag. Nat. Hist., ser. 8, vol. 9, p. 157, 

 1912. Tyjie of genus: Psilozona albitarsis Ricardo, 1912. 

 Designated by Hardy, 1921. 



These flies are of medium size or slightly larger 

 and are related to Phellus Walker. They are charac- 

 terized by the very broad wing base, apically pointed; 

 the appendiculate vein at the base of the second sub- 

 marginal cell; besides the exceptionally wide head, 

 wliich is considerably wider than the thorax. The 

 midtibial spur is present. They are separated from 

 other Dasypogoninae by the absence of spines on the 

 female terminalia and absence of spine on the anterior 

 tibia. From Phellus they are distinguished by the ab- 

 domen being narrow basally and the presence on female 

 terminalia of numerous, short, spinous bristles. 

 Length 18 to 22 mm. 



Head, lateral aspect : The face is comparatively short, 

 very short below the antenna and nearly straight in 

 profile; the ventral portion is exposed chiefly because 

 of the posterior recession of the eye. The eye is more 

 than usually long, strongly convex anteriorly, gently 

 convex posteriorly over the middle portion but rounded 

 and anteroventrally recessive below and above. Pile 

 of the occiput dense, fine and abundant over the whole 

 occiput, becoming longer ventrally ; bristles are absent 

 although the dorsal pile becomes slightly stiffened in 

 character. Proboscis short and robust basally, rather 

 narrowed and attenuate apically but the apex truncate ; 

 the base has numerous short, fine hairs, the apex with 

 minute short pile. The palpus is exceptionally long 

 and cylindrical and reaches almost to the apex of the 

 proboscis; the basal segment is quite short, the first 

 segment fully cylindrical and not excavated; the second 

 not porate and with unusually thick, dense bristles over 

 the whole surface and apex. Antenna attached at 

 the middle of the head, moderately elongate, the first 

 segment nearly twice as long as the second, a little 

 swollen towards the base; second segment beadlike; 

 third segment narrow and attenuate basally, slightly 

 swollen and dilated from the base and widest near the 

 apex; it carries two microsegments, the first quite 

 short, the second longer, oidy slightly narrowed 

 apically and carrying in turn a short, apical spine. 

 The pile of the first antennal segment consists of nu- 

 merous, long, bristly hairs dorsally and numer- 

 ous, still longer, slender bristles laterally and ventrally ; 

 apex of the second segment dorsally with two fine, long, 

 bristly hairs and with one or two below. 



Head, anterior aspect: The subepistomal area is 

 large, but nearly horizontal, quite ' concealed by the 



