LErTOGASTEINAE 



ROBBER FLIES OF THE WORLD 



315 



attached quite far to the rear and all of the coxae lie 

 far forward, and close together. 



Legs: The legs are elongate and slender, especially 

 the hind pair which are especially elongate. Hind 

 femur almost threadlike except on the discal fourth 

 which is dilated and swollen. It bears a fringe of 

 conspicuous, fine, oblique bristles ventrolaterally con- 

 taining about 18 bristles and there is a similar ventro- 

 medial row with at least 25. On the swollen portion 

 of the hind femur are 1 or 2 rows laterally, dorsally, 

 and medially, all of which largely disappear on the 

 slender portion. Hind tibia nearly as long as the femur 

 and with 2 dorsal, 1 lateral, 1 posterior, and 2 ventral 

 rows of similar, regular, numerous, oblique, fine bristles 

 or bristly hairs. Hind basitarsus very long and slender, 

 at least as long as the remaining segments combined 

 and all with similar bristly hairs to those of the tibia. 

 First 4 femora with more scanty pile, the middle pair 

 with a ventral fringe of 15 bristly hairs. These 4 

 tibia have more numerous rows of regularly spaced 

 elements. Claws fine, sharp, barely curved, the pulvilli 

 absent. The empodium is apparently absent and the 

 lateral claw of both hind and middle legs shorter. 



Wings : The wings are rather slender, the second vein 

 and the anterior branch of the third vein are arched 

 backward especially distally. The anal cell is quite 

 widely open and the ambient vein is complete. The 

 venation in every respect is similar to Schildia and all 

 the branches of the radius and the distal branches of the 

 medius and cubitus bear on each side a fringe of con- 

 spicuous microsetae. Halteres clublike on long, slender 

 stalks. 



Abdomen : The first segment is extremely short, the 

 second remarkably long and cylindrical and nearly 

 three-fourths as long as the wing. Remaining seg- 

 ments also slender, long and cylindrical and the end of 

 the abdomen is a little widened and clavate. 



Genus Leptopteromyia Williston 



Fiotjees 198, 586, 1197, 1206, 2040 



Leptopteromyia Williston, Journ. New York Ent. Soc, vol. 15, 

 p. 1, 1907. Type of genus: Leptopteromyia gracilis Willis- 

 ton, fig. 77 (35), figure and name, 1908. Designated by 

 B. Hardy, 1947. Description by Carrera, 1947. 



Small flies of exceptionally slender abdomen and 

 characteristic wing venation. There are only four 

 posterior cells. The third and fourth cells are united 

 into one cell and the anal cell is missing. The post- 

 basal margin of the wing is formed by the anal vein. 

 The short, third antennal segment carries a subdorsal 

 arista and like Schildia Aldrich the halteres are excep- 

 tionally long. Leptopteromyia, Eurhabdws, Aldrich, 

 Schildia Aldrich and subgenus Shannomyioleptus 

 Carrera are all related and share the remarkable 

 halteres. They differ in wing venation and form of 

 antenna, which, however, has a general similarity in 

 all 4 genera. Length 8 mm. 



Head, lateral aspect : The head is long and in lateral 

 aspect subcircular; the eye is extremely large and 

 strongly convex, the face plane with the eye margin. 

 The occiput is moderately developed, a little more 

 prominent dorsally ; it is broadly and strongly rounded 

 and together with the eye is convex posterodorsally. 

 The proboscis is small and cylindrical, extending well 

 beyond the face, thrust obliquely forward, cylindrical, 

 with the apex bluntly pointed. Palpus of one segment, 

 small and short. The antenna is attached at the upper 

 fifth of the head, small and short, the first segment is 

 quite small, the second is larger and beadlike. The 

 third segment is not quite so wide, is a little longer and 

 bluntly truncate at the apex with a comparatively 

 long, slender, dorsal, bristlelike style. 



Head, anterior aspect : The face is extremely narrow 

 on the upper half, the eyes almost touch and are 

 strongly divergent on the lower half with the eyes 

 diverging at the same angle on the posterior ventral 

 portion of the occiput so that from below the cheeks 

 appear wide. Width of upper face less than a twentieth 

 the head width; the whole face is micropubescent, with- 

 out pile, except for 2 rows of slender hairs above the 

 epistoma, each row consisting of 1 pair. Front short, 

 pubescent, triangular, the vertex very little excavated, 

 the small ocellarium is set quite far apart and the eyes 

 are strongly excavated posterolaterally and flared 

 leaving the upper occiput greatly exposed ; this postero- 

 vertical excavation is considerably greater than in the 

 several related genera. 



Thorax : The mesonotum is high and short ; the an- 

 terior margin is abrupt and nearly vertical, the pos- 

 terior end is also quite high and almost vertical. The 

 scutellum and abdomen are attached well below the 

 middle of the thorax. The middle of the mesonotum 

 is broadly polished and shining; the sides narrowly 

 behind the humerus and more broadly over the wings 

 are short, appressed pubescent and almost scaled. 

 The middle of the mesonotum has dorsocentral rows 

 of short, scattered, nearly erect hairs. Laterally there 

 is 1 long, slender, notopleural bristle, 1 supraalar, no 

 postalar and no scutellar bristles; scutellar margin 

 and disc with a few, short, scattered hairs. Meso- 

 pleuron densely, short, appressed pubescent; the upper 

 mesopleuron bears a few, scattered hairs. The hypo- 

 pleuron likewise has 1 or 2 hairs. The metasternum 

 is greatly elongate and appears to extend as a broad, 

 delicate, elongate, thin but chitinous arch with medial 

 seam behind the posterior coxa. The posterior coxa 

 is set so far forward it lies almost beneath the hu- 

 merus. Presternum not dissociated. The halteres are 

 remarkably long. 



Legs : The posterior femur and its tibia are greatly 

 elongate, more than twice as long as the middle pair; 

 its femur is strongly clubbed and dilated on the outer 

 third, and the tibia narrow at base and gradually 

 widened until at the apex it is almost as stout as the 

 femur. The pile of the legs consists of fine, more or 

 less appressed, stiffened hairs. Posterior femur with a 

 ventrolateral fringe of 15 to 20 moderately long, erect, 



