236 



ROBBER FLIES OF THE WORLD 



short, the first more robust, a little longer and both 

 with long, coarse pile above and numerous longer bris- 

 tles below. The third segment is widest at the base, 

 slender, attenuate, more tapered at the apex, with two 

 prominent microsegments nearly as thick as the end of 

 the third segment proper; the first microsegment is 

 short, the second is several times as long and tipped 

 with a spine. 



Head, anterior aspect : The width of the head is mod- 

 erate, wider than the mesonotum ; face quite wide, diver- 

 gent below to a little more than one-third the head 

 width. The whole face is pubescent and, except near 

 the eye, densely beset with long, slender bristles. Sub- 

 epistomal area large, its sides partly bristly. The 

 supraepistomal bristles are not strong. Front fiat with 

 fine pile laterally, slightly divergent. Vertex but little 

 excavated, the ocellarium large, with 5 to 7 long, slen- 

 der, bristly hairs on each side between the ocelli and 

 with 3 stouter bristles between the posterior ocelli and 

 3 or 4 more behind the ocelli. Anterior eye facets 

 strongly enlarged. 



Thorax : The mesonotum on the anterior part is later- 

 ally compressed submedially It is pollinose with abun- 

 dant, long, fine pile; it has a dense, medial mane of 

 long, bristly hair beginning at a level corresponding 

 to the anterior margin of the humerus and continued 

 to the scutellum and containing the dorsocentral bris- 

 tles. The lateral complement of bristles consists of 

 only bristly hair on the humerus, the notopleuron with 

 3 or 4 stout bristles, supraalar with 5 or more slender 

 bristles, and postalar with 7 slender bristles. Scutel- 

 lar margin with 8 or 10 pairs of long, moderately stout 

 bristles and the disc covered with dense, long, crinkly 

 pile. Bristles absent on the pleuron, except perhaps 

 on the metapleuron where there is a wide, vertical 

 band of numerous, long, slender, attenuate, bristly 

 hairs. Propleuron densely long pilose. The posterior 

 mesopleuron and the upper stemopleuron with less 

 abundant hair. Lateral and ventral metasternum 

 densely pilose, the postmetacoxal area membranous. 



Legs : The femora are comparatively short and stout, 

 but little swollen. All are densely long, bristly pilose. 

 Their dorsal surfaces have appressed, shorter pile as 

 well; bristles absent. All the tibiae with fringes of 

 very long, fine attenuate hairs ventrally and pos- 

 teriorly, shorter subappi^essed pile dorsally, and also 

 with abundant bristles. Hind tibia with 5 or 6 long 

 dorsal bristles, 3 similar bristles laterally, and 2 ventro- 

 lateral bristles distally ; the apex has 7 bristles. Middle 

 tibia also with long dorsal, posterior and posteroventral 

 bristles, with about 5 elements in each row. Anterior 

 tibia similar but the dorsal bristles short, oblique, and 

 7 in a row. Anterior tibial apex with distinct, sigmoid 

 spine. Claws sharp, strongly curved from the middle, 

 pulvilli and empodium well developed. 



Wings : The marginal cell is widely open, second sub- 

 marginal cell long and narrow, all posterior cells widely 

 open, anal cell narrowly open. The fork of the third 

 vein is located before the posterior crossvein and the 

 anterior crossvein enters the discal cell a little before 



the outer fourth, which is in contrast to Eucyrtopogon 

 Curran where the fork of the third vein is opposite the 

 posterior crossvein and the anterior crossvein is nearer 

 the middle of the discal cell. Alula is short, gently 

 curved; ambient vein complete. The furcation of the 

 third vein and the crossveins usually with small, 

 blackish spots. 



Abdomen : The abdomen is dense, long pilose on the 

 lateral portion of each tergite, the pile shorter, fine 

 and slightly appressed medially and growing a little 

 shorter terminally. Males with 7 tergites and a minute, 

 liplike trace of the eighth. Females with 8 tergites, 

 the eighth quite short and from a third to a fourth as 

 long as the seventh. Male terminalia rather small and 

 comparatively short; the epandrium is notched medi- 

 ally and indented but not cleft ; it forms a rounded, flat 

 lobe on each side. Gonopod cylindroid, bluntly point- 

 ed, as long as the epandrium. Hypandrium short, ob- 

 tuse, sloping upward. Cavity of the terminalia exposed 

 from below. Female terminalia with 4 or 5 short, stout 

 spines on each acanthophorite. 



Distribution : Nearctic : Comantella cristatus Coquil- 

 lett (1893); fallei Back (1909); patifica Curran 

 (1926) ; rotgeri James (1937). 



For an understanding of the problems involved in 

 the type fixation of this genus the student is referred 

 toMelander (1923) and Curran (1926a). 



Genus Lestomyia Williston 

 Figotes 165, 525, 1103, 1112, 1842, 1867 



Lestomyia Williston, Trans. American Ent. Soe., vol. 11, p. 



19, 1884. Type of genus: Clavator saiulonum Osten 



Saeken, 1877, by original designation. 

 Clavator Osten Saeken, not Philippi, Bull. U.S. Geol. Survey, 



vol. 3, p. 391, 1877. 



Small or medium size flies characterized by the 

 strongly gibbous and convex face, and the bent spine at 

 the apex of the protibia. The third antenna] segment 

 is rather strongly dilated distally; its microsegment 

 ends bluntly and is truncate with an apical pit. These 

 flies resemble Lasiopogon Loew, from which they are 

 distinguished by the tibial spine, presence of lateral 

 metasternal pile and not divergent vertex. Length 

 9 to 14 mm. 



Head, lateral aspect: The head, including the face, 

 is long; the face on the ventral two-thirds or three- 

 fourths is gibbous, convex and sometimes strongly 

 produced, leaving the upper portion beneath the an- 

 tenna short. Occiput very prominent below, due to the 

 marked posteroventral recession of the eye, which 

 begins near the upper third of the head. The occipital 

 pile is long, abundant and coarse ventrally, with a few 

 slender bristles on the upper third of the head, and 

 with a close-set tuft of 5 stout bristles on each side 

 behind the vertex. Proboscis extended well beyond 

 the face, large, cylindroid, with blunt apex and un- 

 usually prominent dorsal carina over the middle por- 

 tion. The middle ventral portion has a number of 



