LAFHRIINAE 



ROBBER FLIES OF THE WORLD 



379 



Distribution : Neotropical : Atractia comata Hermann 

 (1912) ; conjungens Hermann (1912) ; coronata Schiner 

 (1867); dispar Hermann (1912); fulvipes Hermann 

 (1912) ; longicomis Hermann (1912) ; lucida Hermann 

 (1912); marginata Osten Sacken (1887); fminuta 

 Wiedemann (1828) ; nigripes Macquart (1808) ; picta 

 Hermann (1912) ; psilogaster "Wiedemann (1828) ; pul- 

 verulenta Schiner (1867); rubida Hermann (1912); 

 vivax Hermann (1912). 



Ethiopian: Atractia arcuata Curran (1927). 



Genus Eumecosoma Schiner 



Ftguees 290, 681, 1290, 1299 



Eumecosoma Schiner, Verb, zool.-bot. Ges. Wieu, vol. 1C>. p. 673, 

 1866. Type of genus : Laphria plettritica Wiedemann, 1828, 

 by original designation. 



Small, dark colored flies with the abdomen smooth or 

 only faintly punctulate. Third antennal segment long 

 oval but of no great length and with acute apex and 

 also with apical spine. Abdomen quite often subclavate, 

 the basal segments narrowed. End vein of discal and 

 fourth posterior cells nearly aligned, or slightly offset. 

 Length 6 to 12 mm. 



Head, lateral aspect: The head is unusually short. 

 The face is not visible in profile except for a trace 

 below. Upper third of occiput with 6 or 7 long, rather 

 stout, sharp bristles. The proboscis is small, extremely 

 short and subcylindrical. Palpus minute and cylin- 

 drical. The antenna is relatively short with the third 

 segment long oval, ending acutely, and obliquely trun- 

 cate; this truncate portion forms a narrowed cavity 

 with tiny visible spine, some distance back from the 

 spinelike apex of the third segment. First segment 

 with a long, conspicuous, slender, ventral bristle and a 

 few setae; second segment also with a few setae. 



Head, anterior aspect: The eyes are very strongly 

 flattened and the greater part of the anterior facets 

 enormously enlarged. Face quite narrow, with parallel 

 sides and everywhere yellowish pubescent. The bristles 

 of the face are very weak and may consist of an episto- 

 mal mystax of 10 to 16 long, slender hairs; upper face 

 sometimes with 4 to 6 long, fine hairs. Ocellar pro- 

 tuberance with a pair of long, slender, divergent bris- 

 tles, slightly curved backward. 



Thorax: The mesonotum is low and gently convex, 

 gently arched in front with scattered, sparse, fine, sub- 

 erect, pale pile and moderately long, often reddish 

 bristles as follows : 1 notopleural, 1 supraalar, 2 post- 

 alar, and 1 pair of rather close-set scutellar bristles. 

 Scutellum with distinct, preapical crease. The slopes 

 of the metanotum bear 2 or 3 reddish yellow bristles 

 and some additional long hairs. Hypopleuron with 4 or 

 5 long hairs, metapleuron with a wide band of long, 

 divergent, fanlike, reddish yellow, slender bristles; 

 curved downward at apex. Mesopleuron with 2 stout, 

 rather long, reddish bristles; pteropleuron pubescent 

 only. Propleuron at most with 1 fine, weak bristle. 

 Postmetacoxal area chitinized; prosternum not dis- 

 sociated. 



Legs : Hind femur distinctly thickened, especially on 

 the outer half and narrowed at apex. The pile is sparse, 

 except below where there is a dense, erect, fringe of 

 yellow, ventromedial, unmodified pile, matched by a 

 similar fringe on the hind tibia. The dorsal surface, 

 beginning just beyond the middle has 3 stout, reddish 

 bristles; the last one is some distance back from the apex. 

 Lateral surface with 2 stout, rather long bristles, red- 

 dish and curved downward, the more basal one is op- 

 posite the basal element of the dorsal bristles. In addi- 

 tion, ventrally there are 3 or 4 long, reddish, erect hairs 

 chiefly confined to the basal half. Tibia with 2 ex- 

 tremely long, oblique, stout, dorsal bristles; also 2 more 

 slender, lateral bristles at the basal fourth and middle. 

 The ventral aspect has 4 bristles beginning just before 

 the middle and curved, all quite long but quite slender. 

 Apex with long, weak bristles below. Middle femur 

 with 2 weak bristles dorsally near the apex and behind 

 them 3 or 4 closely adjacent, long, reddish, fine, erect 

 hairs. Middle tibia with extremely long, reddish bris- 

 tles, 4 stout dorsal elements, 5 ventral bristles a little 

 less stout and all of them oblique. 



The anterior femur has 2 weak bristles placed dorsally 

 before the apex in a longitudinal row; the ventral mar- 

 gin has 6 or 7 quite long, fine hairs; the anterior tibia 

 has 5 quite long, rather stiff, slightly oblique, reddish 

 ventral bristles ; dorsally there are only 5 weak, shorter 

 bristles; the ventral row is double. The anteroventral 

 and posteroventral rows each contain only 3 long, stout 

 bristles and 1 weak basal element. Anterior basitarsus 

 with 1 very long, posterior, basal bristle ; it and the suc- 

 ceeding segments have equally long, apical bristles. 

 Claws moderately elongate, sharply convex, apically 

 sharp; the pulvilli is four-fifths as long as the claw; 

 empodium long as the claw but slender. 



Wings: The wings are unusually slender. Marginal 

 cell closed with a long stalk. Posterior crossvein rec- 

 tangular to the fourth vein. All posterior cells widely 

 open except the fourth which is closed with a short stalk. 

 The anterior crossvein enters the discal cell at the basal 

 third, or basal fourth. Anal cell closed and stalked. 

 Alula quite narrow. The ambient vein may end at the 

 end of the second posterior cell or even before this point. 



Abdomen: The abdomen is typically not punctulate 

 but distinctly narrowed ; most narrow at the end of the 

 second tergite where the abdomen is scarcely half as 

 wide as the end of the fifth tergite. The first tergite is 

 nearly as long as the second, at least three-fourths as 

 long. Sides of first tergite with a vertical row of 5 very 

 stout, long, reddish bristles. Middle of the lateral mar- 

 gins of the second and third tergites each with 2 and of 

 the fourth and fifth tergites each with 1 long, stout, 

 somewhat curved, pale, subappressed bristle. Sternites 

 with only long, fine pile. There are seven tergites in the 

 male, the seventh is reduced to half the width and length 

 of the sixth; there may be a thin, linear trace of the 

 eighth tergite. Eight tergites visible in the female, the 

 last two are quite short and a fifth or less the width of 

 the sixth tergite. Male terminalia more exposed than 

 in Atomosia Macquart, and rotate and the triangular, 



