316 



UNITED STATES NATIONAL MUSEUM BULLETIN 2 24 



fine bristly hairs. Middle femur with a less copious 

 ventral fringe, 2 or 3 similar, apically directed hairs 

 at the dorsal apex. The middle tibia has an antero- 

 ventral, a very short anterior and short posterior row 

 of fine, bristly hairs, each row containing about 15 

 elements. Anterior legs similar ; the first two segments 

 of the anterior and middle tarsi bear somewhat stouter, 

 bristly hairs. Claws long, sharp, gently curved and 

 partly apposed; the empodium is reduced to half the 

 claw length on the first four legs, a little longer and 

 stouter on the hind pair. 



Wings: In the wings the anal area and the whole 

 basal half of the wing more or less reduced. The 

 first vein ends before the end of the discal cell; the 

 anterior branch of the third vein arises rather ab- 

 ruptly from the third vein and the second submar- 

 ginal cell is wide at the base. The anterior crossvein 

 enters the discal cell at or before the middle. The 

 third and fourth posterior cells have united into one, 

 the entire anal lobe has disappeared leaving the pos- 

 terior border formed by the anal vein. Ambient vein 

 complete. 



Abdomen: The abdomen is long and quite slender, 

 especially on the second and third segments, which 

 are cylindrical. Pile is short, scanty, subappressed 

 and setate; the sides of the first tergite bear several 

 moderately stout bristles. Male terminalia with well 

 developed, elongate superior forceps hooked apically, 

 with the point turning toward the medial plane. The 

 gonopod is almost as long as the superior forceps. 

 Hypandrium prominent and long, deeply sulcate, the 

 lateral arms bear bristles. 



Hermann (1926) proposed the species Leptoptero- 

 myia willistoni Hermann as type of genus, without, 

 however, describing it. Williston (1908) figured a 

 species under the name Leptopteromyia gracilis and 

 this illustration validates the genus. Carrera (1947) 

 offers a description. E. Hardy (1947) discusses the 

 genus Leptopteromyia and correctly observes that it is 

 well founded. He also points out that the type of genus 

 is Leptopteromyia gracilis Williston from Brazil. 



Distribution: Nearctic: Leptopteromyia americana 

 E.Hardy (1947). 



Neotropical: Leptopteromyia gracilis Williston 

 (1908). 



Genus Eurhabdus Aldrich 



Fiqubes 587, 1196, 1205, 2037 



Evrhaldus Aldrich, Proc. U.S. Nat. Mus., vol. 62, p. 2, 1923. 

 Type of genus: Eurhabdus zephyreus Aldrich, 1923, by 

 original designation. 



Strange flies in which the basal part of the wing 

 for almost precisely half the total wing length is re- 

 duced to a remarkably slender, hairlike stalk, bearing 

 a few, fine cilia on each side. The discal, second, third 

 and fourth posterior cells are combined into one cell. 

 The greatly expanded eyes meet in front for a consid- 

 erable distance below the minute antennae, almost re- 

 ducing the face to none and making the only holoptic 



genus in Asilidae. The thorax is quite small and 

 short and not much bigger than the head. The hal- 

 teres are like round, flattened discs attached by very 

 long, slender, threadlike stalks, each longer than the 

 middle tibia. Abdomen extraordinarily slender and 

 elongate. Length Q 1 ^ to 12 mm. 



Head, lateral aspect: The head consists mostly of 

 the greatly enlarged eyes; the length is medium, the 

 occiput moderately developed over the middle of the 

 head with a few, fine, minute hairs. Face not visible 

 in profile. The proboscis is small, extending beyond 

 the head for a short distance, directed forward, cy- 

 lindrical and tapered to a blunt point on the outer 

 fifth. Palpus minute. The antenna is attached at 

 the upper eighth of the head, or on nearly the same 

 plane as the ocelli. They are extremely short and incon- 

 spicuous. Front small, the vertex scarcely excavated, 

 the ocellarium quite low. From the dorsal view the 

 eyes are flared and rounded outwardly, exposing a 

 wide area of upper occiput and postvertex. The vertex 

 is therefore strongly divergent. The anterior eye fac- 

 ets are greatly enlarged. 



Thorax : The thorax is polished and shining with a 

 few, scattered, miscroscopically small setae. The mes- 

 onotum is high and sloping steeply behind; it is 

 abrupt anteriorly and slightly overhangs the pronotum. 

 Humerus bare; the lateral complement of bristles, all 

 fine and slender, includes 1 notopleural, 1 postsupra- 

 alar, apparently no postalars, and only 1 pair of 

 scutellar bristles. Pleuron and the supraalar region 

 micropubescent. Postmetacoxal area fused into a long, 

 stout, pubescent, chitinous arch. Halteres large, their 

 stalks extremely long and slender. 



Legs: The hind femur is greatly elongate, almost 

 as long as the very long first abdominal segment and 

 on the apical fifth it is strongly swollen and clavate. 

 The hind tibia is as long and as slender as the femur 

 and a little thickened on the distal fourth. Hind 

 tarsus but little elongate. The pile of the hind femur 

 consists of fine, sharp, scattered, subappressed setae 

 and a single small bristle dorsomedially at the apex. 

 Middle anterior femur a little swollen near the apices ; 

 the middle femur has an anteroventral fringe of 10 

 to 12 very fine, slender bristles; the tibia has similar 

 but fewer elements. The anterior tibia also has such 

 fine bristles. Anterior tarsus with comparatively 

 stout bristles anteriorly. Pulvilli absent; the claws 

 slightly curved, sharp, partly apposed; the empodium 

 half the claw length. 



Wings: The discal, second, third, and fourth pos- 

 terior cells are combined into one cell. Aldrich (1923) 

 was mistaken in stating that the auxiliary and first 

 longitudinal veins are absent. Actually both of these 

 veins are present, but are so crowded together with 

 the costa that they appear as one. Close inspection 

 will show that these veins are present and that there is 

 a minute space between them. The radius then, is 

 4-branched, with only 3 apparent branches. The discal 

 cell is widely open to the margin and marginally flared, 

 gradually increasing in width from the base. The 



