DASTPOGONINAB 



ROBBER FLIES OF THE WORLD 



273 



Genus Omninablautus Pritchard 



Figotes 102, 518, 1121, 1130 



Omninablautus Pritchard, Amer. Mus. Novitates, no. 813, p. 1. 

 1935. Type of genus: Omninablautus arenosus Pritchard, 

 1935, by original designation. 



Small flies characterized by the short, high mesono- 

 tum, dense pollen and a transverse shieldlike mat of 

 dense pile across the middle of the face. The pulvilli 

 are lacking, the claws sharp, very slender and only 

 slightly curved. The anterior tibia has a distinct, 

 slender, black, sigmoid spine which at once separates 

 these flies from Ablautus Loew to which they are either 

 related or convergent. From Hodophylax James they 

 are separated by the long dorsocentral bristles and long 

 ventral antennal bristles. Length 5-8 mm. 



Head, lateral aspect: The face is very slightly pro- 

 duced and elevated in profile and gently rounded; the 

 eye is narrowly recessive anteriorly on the ventral pos- 

 terior third of the head, strongly convex anteriorly, 

 wider below and gently convex behind. The occiput is 

 obliterated on the upper half, moderately prominent 

 below with no pile dorsally but with rather abundant, 

 moderately long, stiff pile ventrally. Bristles begin 

 at the middle of the head and consist of 5 weak pairs, 

 but dorsally, behind the vertex, there are 5 or 6 stout, 

 straight bristles in a transverse row. Proboscis small, 

 rather robust, cylindrical, very slightly tapered to a 

 blunt apex and bearing a number of fine hairs distally 

 in the ventral midline and others at the tip. There are 

 3 or 4 fine, long hairs ventrally in the middle. The pro- 

 boscis is directed almost but not quite horizontally for- 

 ward. Palpus minute, clearly composed of two seg- 

 ments. First segment with a few delicate hairs 

 ventrally, dorsally and laterally. The second segment 

 is short with a fine, ventroapical bristle. The antenna 

 is attached at the middle of the head, moderately 

 long, the first segment a little shorter than the 

 second, the latter widened apically. The third seg- 

 ment is slender, nearly cylindrical, of almost uni- 

 form width, perhaps slightly wider near the base and 

 beyond the middle; its apex is slightly nar- 

 rowed and bears a minute microsegment followed by a 

 slightly longer one which carries an apical spine. First 

 segment and the second with 2 or 3 stiff, appressed setae 

 dorsally; the first bears long, ventral bristles below; 2 

 of which are comparatively stout; these are nearly as 

 long as the third segment. Second segment with 1 

 slightly shorter, stiff bristle below. The third antennal 

 segment is not quite twice as long as the first two 

 combined. 



Head, anterior aspect: The face below antenna is 

 nearly one-third of head width, with parallel sides or 

 at most very slightly divergent; subepistomal area 

 small, deeply concave and bare. Cheeks between the 

 eyes and the epistoma with a deep, narrow fissure. 

 Face densely appressed micropubescent, and bearing a 

 dense mat of long, downwardly directed pile which is 

 situated on a triangular area reaching nearly to the 



antenna. Hidden beneath the mat is a fringe of epis- 

 tomal bristles and there are 2 or 3 bristles along the 

 side margins of the subepistoma. The front is slightly 

 divergent, long and spacious; the vertex at most very 

 slightly convergent and shallowly excavated. In this 

 respect these flies suggest Stichopogon Loew, although 

 the front is not so wide above. There is nevertheless a 

 strong similarity. Sides of the front with 3 or 4 stiff 

 hairs; ocellarium large, conspicuous, with steep sides 

 and large ocelli and bearing centrally 2 pairs of stout, 

 long, divergent bristles and at the corner of the posterior 

 ocelli with 2 additional bristles. Eye facets strongly 

 enlarged centrally. 



Thorax: The mesonotum and pleuron densely pol- 

 linose. The pile is very scanty and composed of 

 moderately long, suberect, bristly hairs. Humerus 

 without pile but with 5 bristles and an acrostical row 

 present and also tuberculate dorsolateral bristles which 

 are strong, long and stout anteriorly as well as pos- 

 teriorly, each row containing 7 or 8. On the lateral 

 margins there are 2 notopleural, 1 postmedial humeral, 

 and 1 medial humeral bristle. There is a single, long, 

 stout supraalar, 2 or 3 postalar and 3 pairs of scutellar 

 bristles. Scutellum moderately thick, flat on the basal 

 half, strongly sloping beyond, pubescent and apilose. 

 Propleuron with dense, tufted, coarse pile matching that 

 upon the occiput; the posterior upper section has similar 

 dense pile which is matted and appressed and directed 

 backward for the most part. Mesopleuron and sterno- 

 pleuron, pteropleuron and hypopleuron without pile, 

 Metapleuron with a double vertical row of numerous, 

 fine, long, fanlike bristles. Metanotal slopes micro- 

 pubescent only ; metasternal slopes with 15 or 20 long, 

 fine hairs; metasternum apilose. The postmetacoxal 

 area membranous; tegula pubescent only. 



Legs: All the femora are stout, the anterior and to 

 a lesser extent the middle pair slightly thickened 

 towards the base, their pile dense, matted, flat ap- 

 pressed, coarse and somewhat flattened. The hind 

 femur bears on the outer half an oblique, assymetrical 

 row which includes near the middle a lateral, beyond it 

 a dorsolateral, beyond that a higher dorsolateral, 

 followed by near the apex a pair of dorsal, and at the 

 apex 2 shorter, smaller dorsal bristles. There are also 

 4 relatively long bristles in a lower, lateral row and 

 there are 5 ventrolateral, and 3 or 4 ventral bristles. 

 Medial and anterior surfaces of this femur with the 

 coarse, matted, appressed pile absent and its place 

 partly taken by a few minute delicate setae. Hind tibia 

 with 5 long, stout dorsal, 4 medial, 2 dorsolateral, 1 

 strong lateral at the apical third, 5 ventrolateral, and 

 2 ventral bristles, all strong on the outer fourth. 

 Medially on this tibia there is scattered pile similar to 

 the other coarse pile and only at the apical eighth is 

 there a brush of setae. Apex with 1 dorsal, 1 dor- 

 solateral, 1 lateral, 4 or 5 ventral and 3 medial bristles. 

 Middle femur with 2 pairs of weak dorsal bristles 

 near the apex, 5 posteroventral, 5 or 6 anteroventral 

 bristles. This tibia has 4 dorsal and 5 anterior bristles, 

 the last two are long, 5 long posterior and 4 or 5 weak 



