DASTPOIiONINAE 



ROBBER FLIES OF THE WORLD 



171 



eye margin, covered with long, somewhat curved pile 

 varying from fine and delicate to stiff hairs or not in- 

 frequently slender bristles which may become a little 

 more stout in character above the epistomal margin. 

 The front is slightly divergent, densely pubescent along 

 the eye margins or sometimes over the whole front. 

 The entire front is covered with abundant, long, fine 

 pile; the vertex but little excavated, the ocellar pro- 

 tuberance low, carrying large ocelli and 2 or 3 pairs of 

 long, slender bristles, of which 1 pair may be accentu- 

 ated, and some additional pile. Eye facets centrally 

 enlarged. 



Thorax : The thorax is dully pollinose or moderately 

 shining, often with pattern of spots and stripes of 

 dense, appressed, micropubescence or pollen. The pile 

 of the mesonotum varies from dense, fine, erect pile 

 over the whole mesonotum, rather long in character 

 and sometimes with the middle portion appressed, to 

 species in which the pile is of similar character, though 

 shorter, but rather scanty. Acrostical bristles or hairs 

 are present, poorly differentiated from the remaining 

 pile. The pile on the posterior half of the mesonotum 

 is usually only slightly longer; the dorsocentral ele- 

 ments are poorly or not at all differentiated. Humeral 

 pile long and abundant and the following complement 

 of lateral bristles present : 1 to 3 long, slender or stout 

 notopleural, 2 or 3 slender supraalar, 3 or more slender 

 postalar, and 7 or 8 pairs of scutellar bristles. In some 

 species these lateral bristles are rather stout and fewer 

 in number, with 2 notopleural, 3 supraalar, 1 postalar, 

 and 2 to 4 fine, marginal scutellar elements. Surface of 

 scutellum convex, with abundant, long, fine or stiff pile. 

 The propleuron bears especially abundant, long, mat- 

 ted tufts of pile. Pronotal collar with a wide band of 

 stiff pile but without true bristles. The posterior half 

 of the mesopleuron and the upper posterior corner of 

 the sternopleuron bear abundant, long, fine pile ; ptero- 

 pleuron and hypopleuron apilose, except that the upper 

 anterior hypopleuron in the type of genus carries a con- 

 spicuous tuft of moderately stiff, short pile. Metapleu- 

 ron with a wide middle band of long, slender bristles. 

 Metanotal slopes micropubescent only; lateral slopes 

 of metasternum with dense, long pile, the metasternum 

 proper is chitinized and bears abundant, long pile. 

 Postmetacoxal area membranous; tegula with numer- 

 ous, stiff bristles in the type of genus. Prosternum 

 dissociated. 



Legs : The femora are moderately stout without being 

 dilated. In the type of genus they bear rather dense, 

 long, fine pile chiefly erect or more or less suberect 

 dorsally, or in the more short pilose species reduced in 

 content. The femora tend to lack conspicuous bristles, 

 and such bristles as are present are quite weak and little 

 more than stiff hairs. The tibiae are notable for abun- 

 dant, long, stiff bristles. The type of genus shows the 

 following complement of bristles: hind femur with 2 

 stout bristles near the middle laterally, the ventral 

 fringe of pile abundant ; middle femur with 4 anterior 

 bristles before the middle and 2 or 3 weak bristles an- 

 teriorly near the apex; the anterior femur is rather 



similar to the middle pair. Hind tibia with well de- 

 veloped bristles, 5 ventrolateral, 8 to 10 doisomedial, 8 

 dorsolateral ; confined to its outer half are 4 lateral and 

 4 ventral bristles. The apex bears 4 medial, 1 dorsal 

 subapical, 2 lateral, and 5 ventral bristles. Remaining 

 pile of hind tibia long and fine. Middle tibia with 7 or 

 8 anterodorsal, 6 to 8 posterodorsal, and between these 

 rows there may be inserted 3 or 4 additional bristles; 

 and with 7 or 8 posterior, 5 or 6 ventral, and 3 or 4 

 anteroventral bristles. The apical circlet has 13 bris- 

 tles with 6 on the ventral half. Anterior tibia and 

 apical circlet rather similar to the middle pair; anterior 

 bristles are absent, the dorsal bristles shorter. Apex 

 of anterior tibia without spine. Tarsi end in sharp, 

 slender claws, well developed pulvilli and empodium 

 strongly thickened at the base. 



Wings : The marginal cell widely open ; all posterior 

 cells and the anal cell widely open. Second basal cell 

 ends in three veins, the upper and lower end veins 

 of the discal cell of nearly equal length. Alula small; 

 ambient vein complete. 



Abdomen : The abdomen varies from wide and robust 

 to species in which it is slightly less wide than the meso- 

 notum and gently tapered to an obtuse apex. The ab- 

 dominal pile varies from microscopic, short setae in 

 some species to others winch have long pile on the first 

 three tergites, becoming progressively shorter and more 

 scanty until there is only a little fine, short pile termi- 

 nally. In the male eight tergites present, the seventh 

 and the eighth both shortened to half or less than half 

 the length of the sixth. Female with eight tergites in 

 the type of genus, the eighth being quite short and 

 virtually concealed by the seventh ; it is a little longer in 

 other species. Male terminalia rotate to a variable ex- 

 tent, usually about one- fourth to the left, sometimes not 

 at all. The obtuse epandrium may be fully cleft or 

 only notched or sulcate near the apex; in either case 

 strongly divergent with the short proctiger placed be- 

 tween. Gonopod prominent, long, obliquely thrust up- 

 ward, and the hypandrium long and broad and convex. 

 Female with 5 or 6 pairs of short spines on the acan- 

 thophorites which protrude but a short distance and are 

 weakly developed. 



Cyrtopogon is a dominant, Holarctic genus. There 

 are numerous species in Europe and there is a still 

 greater concentration in the Pacific coastal states of the 

 United States. The species Cyrtopogon africanus is 

 atypical but as I have only a female to study, I prefer 

 to leave it in this genus for the present. These flies 

 frequent low growing shrubs on the edges of forested 

 areas and may be abundant on the bark of logs deep 

 within forests. 



Distribution: Nearctic: Cyrtopogon ablautoides 

 Melander (1923); albifacies D. E. Johnson (1942); 

 albifrons Wilcox and Martin (1936) ; albovarians Cur- 

 ran (1924) [ = albitarsis Curran (1923) female]; al- 

 drichi Wilcox and Martin (1936) ; aUeni Back (1909) ; 

 anomalus Cole (1919); auratus Cole (1919) [=albi- 

 stylus Curran (1922) male]; aurifex Osten Sacken 

 (1877) ; auripilosus Wilcox and Martin (1936) ; banlesi 



