DASYPOGONINAB 



ROBBER FLIES OF THE WORLD 



173 



ners. It bears abundant, fine pile on the lower half 

 and quite weak, anteriorly curved bristles on the upper 

 half. The proboscis extends little if any beyond the 

 base and is quite obtuse at apex with a low, dorsal 

 ridge. The palpus is clearly composed of two seg- 

 ments, the first segment excavated, the second of the 

 same length, robust and a little narrowed at the apex, 

 with apical pore and only with fine hairs. The an- 

 tenna is attached below the upper third of the head; 

 the first segment is twice as long as wide, the second 

 segment is one and a half times as long as wide and 

 widened distal ly. The third segment is narrowed 

 slightly beyond the base and again at the apex; with- 

 out microsegment it is iy 2 times as long as the com- 

 bined length of the first two segments. It bears a 

 short, stout microsegment followed by a considerably 

 longer, equally stout, apically narrowed microsegment 

 with short, apical bristle; both microsegments are di- 

 rected obliquely downward. First and second seg- 

 ments with short setae above, the first with long, bristly 

 hairs below, the second with 2 long, slender bristles and 

 1 or 2 hairs ventrally. 



Head, anterior aspect: The width of the head is 

 about 1% times the height of the head. The face 

 below the antenna is one-fifth the width of the head 

 and slightly wider below. It bears coarse, appressed 

 pubescence and no pile but numerous, long, very slen- 

 der bristles; and there are only 1 or 2 stout elements 

 in the middle on the epistomal margin. Front dis- 

 tinctly wider than the face; the vertex is slightly 

 narrowed, shallowly excavated with large, dorsally 

 rounded ocellarium; its sides are vertical and bear 3 

 or 4 pairs of slender bristles between the ocelli and 1 

 or 2 pairs behind, all of them long. The front is 

 sunken in the middle, pubescent with considerable long, 

 bristly hairs. 



Thorax: The thorax is short and moderately high, 

 the mesonotum is pollinose, with a differentiated dou- 

 ble row of acrostical setae and numerous, long, coarse 

 setae laterally. Dorsocentral bristles begin just before 

 the suture and form 4 long, moderately stout elements 

 behind. Lateral bristles are rather stout and finely 

 attenuate; there are 3 long notopleural in an oblique 

 row, 4 above the wing, 3 long and 2 weak elements on 

 the postalar callosity, and 3 pairs of stout bristles on 

 the scutellar margin. The scutellum is not quite flat 

 with deep basal crease, the surface coarsely appressed 

 pubescent but no pile. The margin, however, is shin- 

 ing. Upper posterior comer of mesopleuron with 

 a few short, bristly hairs, the dorsal margin with some 

 stiff hairs. Pronotum with weak bristles. Metapleu- 

 ron with a vertical band of numerous, long, slender 

 bristles and bristly hairs. Postmetacoxal area mem- 

 branous, the lateral and ventral metastemum has long 

 pile. Presternum fully dissociated. 



Legs: All the femora are stout, polished, with abun- 

 dant, coarse, appressed setae dorsally. Posterior fe- 

 mur with an erect fringe of ventromedial hairs 

 containing also some longer hairs. Bristles are re- 

 stricted to some 6 or 7 short, slender bristles dorso- 



laterally. Hind tibia narrow only at the base; and 

 is stout and swollen beyond. It bears 5 moderately 

 long, stout, lateral bristles, several small, short, dorso- 

 lateral basal elements, and 2 longer dorsomedial ele- 

 ments on the discal third. Hind basitarsus swollen, 

 longer than the next two segments, which are also 

 somewhat swollen. Middle femur with a weak, short 

 bristle on each side subapically and dorsally. Middle 

 tibia with 3 quite short and 2 rather long, stout antero- 

 dorsal bristles on the basal half but with 7 rather 

 l° n g> posterior or perhaps posteroventral bristles, and 

 2 equally long ventral bristles on the outer half. An- 

 terior femur with some short, bristly hairs posteriorly ; 

 the tibia has 3 or 4 quite short bristles anterodorsally 

 on the apical half and also 7 pale, posterior bristles 

 similar in length to those on the middle tibia and 

 neither group long. It also has 3 comparatively long, 

 attenuate, posteroventral bristles. Apex without spine. 

 Claws slender, bent chiefly at the apex and sharp; 

 pulvillus long and narrow; and empodium short and 

 stout. 



Wings : The wings are slender, greyish hyaline with 

 darker villi everywhere, except in the base of the basal 

 cells and costal cells. Marginal cell widely open, the 

 anterior branch of the third vein ends above the wing 

 apex. All the posterior cells quite widely open, the 

 anal cell narrowly open or closed in the margin. The 

 anterior crossvein enters the discal cell at the middle, 

 the posterior crossvein is short, the third vein forks 

 opposite the end of the discal cell. Alula quite nar- 

 row, ambient vein complete. Second submarginal cell 

 quite slender towards the base and also not wide 

 apically. 



Abdomen: The abdomen is moderately wide at the 

 base and not quite as wide as the mesonotum. The 

 second segment has a deep fossa. The abdomen is 

 shining with scanty, appressed, fine setae and pollinose 

 spots laterally and posteriorly on the tergites. Sides 

 of the first segment with 4 or 5 long, quite slender 

 bristles and some shorter pile. Males with eight ter- 

 gites; the eighth, however, is only one-third as long 

 as the seventh and the seventh half as long as the 

 sixth. The male terminalia are quite small and short 

 and partly rotate. The epandrium is exceptionally 

 small and short and uncleft, with the small proctiger 

 protruding beyond. The gonopod is prominent but 

 short, the hypandrium short but quite broad. 



Distribution : Palaearctic : Lithoeciscus heydeni Loew 

 (1871). 



Genus Nannocyrtopogon Wilcox and Martin 



Figures 166, 489, 986 



Nannocyrtopogon Wilcox and Martin, Ann. Ent. Soc. Amer., vol. 

 29, p. 449, 1936. Type of genus: Cyrtopogon cerussatus 

 Osten Sacken, 1877, by original designation. 



Small or very small flies of bare aspect with reduced 

 pile, especially upon the abdomen. Separated from 

 Cyrtopogon Loew by the bare scutellum which has 



