ROBBER FLIES OF THE WORLD 



471 



Thorax: The thorax is brownish yellow poUinose, 

 especially pronouiaced on the scutellum. Bristles of 

 the lateral margins and pile of humerus, scutellar disc, 

 and metanotal slojies black. Metapleuron with an 

 irregular, vertical row of 6 black bristles and anteriorly 

 with numerous, long, yellow hairs; 9 long, weak, black 

 bristles on hypopleuron; pronotum with 8 pairs of 

 slender, black bristles. 



Legs : The legs are black and black pilose, except for 

 a little pale pile posteriorly on the first 4 femora, and 

 all bristles black. Mats of setae on anterior tibia and 

 tarsi conspicuously rust brown. 



Wings: The marginal and submarginal cells are 

 rather strongly rippled. The two branches of the third 

 vein end rather close together; the posterior branch 

 ends immediately below the apex. 



Abdomen : The first tergite has a prominent, dense, 

 wide band of very fuie, brownish yellow pile and has 

 7 or 8 weak but long, brownish yellow bristles. 



Type. Male; allotype female, Tonkin, Than-Moi, 

 June-July, H. Fruhstorfer collector. Both types are in 

 the Zoologische Staatssammlung, Munich. 



Genus Porasilus Curran 



FiOTJEES 314, 709, 1386, 1397, 2477, 2487 



Pofasiliis Curran, Amer. Mus. Novitates, no. 7.52, p. 15, 1934. 

 Type of genus : Porasilus barbiellinii Curran, 1934, by origi- 

 nal designation. 



Flies of medium size or larger. Eelated to and re- 

 sembling Nerax, new genus in general appearance ; like 

 those flies the abdomen is stout basally and the male 

 terminalia large and clublike. Facial gibbosity very 

 promment with an abrupt ledge above and occupymg 

 at least tliree-fourths the height of the face and well 

 covered with long, slender bristles; lower facial ele- 

 ments more stout and sides of the long, narrow subepis- 

 tqma covered with a broad band of bristly pile. The 

 posterior branch of the third vein ends below the wing 

 apex and the base of the second submargmal cell has a 

 spur vein. Ninth male sternite with a curious, not chiti- 

 nized, ventral lobe or projection, which is small but 

 distmct. The female terminalia is long and laterally 

 compressed. Its principal distinction from Nerax lies 

 in the presence of a patch of scattered pile on the lat- 

 eral metanotal slopes. Length 18 to 20 mm. 



Head, lateral aspect : The head is comparatively long 

 with the face strongly produced and gibbose and with 

 an abrupt ledge above. The upper third of the face is 

 short and extends only a little beyond the eyes. The 

 proboscis is only moderately stout; it extends a little 

 beyond the face and is directed chiefly downward ; it is 

 blunt with numerous, bristly hairs at the apex which 

 extend outward and it has a subapical crease. Palpus 

 robust, elongate, large and bearing numerous stout 

 bristles and bristly hairs, which are black or pale. The 

 antenna is attached near the upper third of the head 

 with the first segment rather slender, nearly twice as 



long as the second. The third segment is as long or not 

 quite as long as the first segment and is a little narrowed 

 apically. It beai-s a stout style as long as all tlu-ee seg- 

 ments combined and has a bristle at the apex. First 

 segment with slender bristles above and longer bristles 

 and bristly hairs below. Second segment with 2 or 3 

 more conspicuous, dorsoapical bristles and 2 or 3 setae 

 below. Cheeks rather prominent, well developed below 

 the eye. The occiput is promuient dorsally but sublat- 

 erally, although the lower fourth of the eye is strongly 

 recessive anteriorly, the occiput is poorly developed 

 below. Ventral pile of occiput is long and fine behind, 

 coarse anteriorly. Weak bi-istles begin at the middle 

 of the head and behind each upper eye corner there are 

 •i stout bristles. 



Head, anterior aspect: The face is rather densely 

 pollinose without pile on the short portion beneath the 

 antenna. The gibbosity bears dense, numerous, slender 

 bristles and bristly hairs down the middle ; some upper 

 elements are black, the lower bristles and hairs pale- 

 In the middle on the lower part of the gibbosity are 

 about 5 quite stout bristles on each side. Stiff hairs 

 extend laterally almost to the eye margin and also down 

 the sides of the subepistoma. The head is widest below, 

 the face below the antenna is about a fourth the head 

 width and strongly widened ventrally. The front is 

 very slightly widened, the vertex slightly narrowed. 

 Sides of front with an oval patch of many, long, slender 

 bristles and bristly hairs. The ocellarium is not large, 

 is low, the anterior ocellus quite small and it bears be- 

 tween the ocelli 3 paire of slender bristles and 2 pairs 

 behind. The vertex is deeply excavated. 



Thorax : The thorax is short and high, the mesonotum 

 is high and rather strongly convex anteriorly and pos- 

 teriorly. It has a wide band of bristly acrostical pile. 

 Dorsocentral elements are merged with lateral hairs 

 anteriorly, are differentiated in the middle of the 

 mesonotum, and form long, slender elements posteriorly. 

 Lateral bristles are stout. There are 2 iiotopleural and 

 2 supraalar bristles, and 2 bristles on the postalar callo- 

 sity. On the scutellar margin are 2 pairs of bristles, 

 besides other long, slender, bristly, marginal hairs. 

 Scutellum convex, thick, without impressed rim; it is 

 pollinose and in the male the disc bears nmnerous, long, 

 quite fine hairs ; females may have some erect setae as 

 well as some long, bristly hairs. Lateral metanotal 

 callosity with bristly pile. The pronotum is long, ex- 

 tending back into the mesonotum in the middle. It 

 bears weak bristles. Posterior margin of mesopleuron, 

 its upper and anterior border, and tlie upper posterior 

 sternopleuron with coarse and bristly haire. Anterior 

 and posterior basalare without pile. Posterior ptero- 

 pleuron with pile. The metapleuron bears a wide ver- 

 tical band of moderately stout, long bristles continued 

 below on the hypopleuron. Lateral metasternum with 

 pile, the ventral metasternum with dense, long pile. 

 There appears to be an extension of the lateral cliitm 

 immediately beliind the posterior coxa. However, it 

 is narrowly separated in the middle and not fused. 

 Prosternum dissociated. 



