DASYPOGONINAE 



ROBBER FLIES OF THE WORLD 



189 



and second segments with a number of long, stiff hairs 

 ventrally. 



Head, anterior aspect. : The face below antenna one- 

 third the head width and slightly divergent below. 

 Subepistomal area large, bare, concave, strongly 

 oblique and more or less concealed by the dense over- 

 hanging mystax. The face is not pubescent, except 

 narrowly along the eye margin, in the type of genus. 

 The pile of the face is very dense, including numerous, 

 long, slender bristles found over the whole of the face ; 

 those above are directed nearly straight outward, those 

 below still more dense and together with the pile 

 form a ventral, oblique mat extending down over the 

 subepistomal area. The front is short, not pubescent 

 but densely long pilose, the lateral pile stiffer and al- 

 most, bristly. Vertex rather deeply excavated, the 

 ocellarium large with steep sides and a pair of long, 

 stout, divergent bristles and additional long pile. Eye 

 facets rather strongly enlarged centrally. 



Thorax: The thorax is pollinose on the mesonotum 

 but more or less bare posteriorly, the pleuron polished 

 and bare. The pile of the mesonotum is dense, rather 

 long, subappressed and shaggy, with lateral bristles as 

 follows: 4 notopleural, 5 supraalar, 12 or 15 slender 

 postalar, and 6 pairs of long, slender scutellar mar- 

 ginal bristles. These numbers are reduced in some 

 species. Propleuron with dense tufts of long pile on 

 all portions, the collar with pile only. Upper posterior 

 mesopleuron, the hypopleuron and the metapleuron 

 each with a dense tuft of long pile. Metanotal slopes 

 micropubescent only. Lateral metasternum with pile, 

 ventral metasternum with abundant long pile. Post- 

 metacoxal area membranous; tegula with bristles. 



Legs: The hind femora are especially stout; all the 

 femora and the tibiae bear dense, bushy pile obscuring 

 the bristles in the type of genus. In the type of genus 

 is the following complement of bristles: on the hind 

 femur 2 lateral apical, 1 subapical, and 2 medial sub- 

 apical; hind tibial bristles long and stout, 6 dorsal, 7 

 lateral bristles. The middle femur has 3 bristles an- 

 teriorly at the apex and 2 posteriorly, its tibia with at 

 least 6 dorsally, 9 or 10 anteriorly, 6 or 7 posterodor- 

 sally, and approximately the same number posteriorly. 

 Anterior femur with 3 anteriorly at the apex and 2 

 posteriorly; anterior tibia with 9 anterodorsally, 6 

 dorsally, 8 posteriorly, apex of tibia without spine. 

 Tarsal segments short and stout, ending in very stout, 

 sharp claws curved from the base, long pulvilli and 

 empodium. 



Wings: The wings are broad; the marginal cell is 

 widely open ; the anterior branch of the third vein ends 

 above the wing apex, the posterior branch behind the 

 apex. The first posterior cell is widely open and wider 

 at the margin than in the middle, the second therefore 

 slightly narrowed; the fourth is narrowed to half its 

 width. Anal cell closed with a short stalk or narrowly 

 open. The second basal cell ends with a short middle 

 vein. Alula of medium width ; ambient vein complete ; 

 villi absent. 



Abdomen : The abdomen is broad and robust as wide 

 as the thorax and more or less flattened. Male with 

 eight tergites, the last three tergites each slightly re- 

 duced in length. Female with eight tergites. Pile of 

 the abdomen is short, flat appressed in the middles of 

 the tergites or in the type of genus long and matted 

 laterally and in the posterior corners. Sides of the 

 first tergite with 3 or -1 weak bristles. Remaining ter- 

 gites without bristles or with tufts of several bristles 

 laterally on each tergite except the last two. Male 

 terminalia short and not rotate; it has 2 short pubescent 

 flaps which turn downward. The female has 3 or 4 

 pairs of stout, short, spoonlike spines. 



Distribution: Neotropical: Pycnopogon divisus Co- 

 quillett (1902). 



Palaearctic: Pycnopogon anthophorinus Loew 

 (1847); apicalis Matsumura (1916); apiformis Mac- 

 quart (1849) ; larrus Walker (1849) ; denudatus Seguy 

 (1949) ; fasciculatus Loew (1847) ; hatakeyamae Mat- 

 sumura (1916); laniger Dufour (1833); leucostomus 

 Engel (1930) ; melanostomus Loew (1874) [ = hirsutus 

 Becker in Becker and Stein (1913)]; mixtus Loew 

 (1847); ndJekoensis Matsumura (1916); pallidipennis 

 Brulle (1832) [=apiformis Loew (1847)]. 



Genus Sisyrnodytes Loew 



Figures 106, 501, 1031, 1040 



Sisyrnodytes Loew, Neue Beitrage . . ., pt. 4, p. 40, 1856. 

 Type of genus : Acnephalum brevis Macquart, 1838, as 

 Sisyrnodytes floccus, by monotypy. 



Small, exceptionally stout, robust flies with short, 

 compact abdomen, and a large thorax, dominated by 

 the high, convex mesonotum. The pile is coarse, some 

 of it crinkled but much of it in the character of slender, 

 weak, bristly hairs. Podal bristles abundant and stout 

 but rather short. Eyes distinctly flattened. This genus 

 is characterized by the fact that several of the posterior 

 veins are atrophied toward the wing margin, the first 

 and fourth posterior cells closed. The ambient vein 

 absent ; pulvilli absent. Length 8 to 12 mm. 



Head, lateral aspect: The face is not at all visible 

 in profile. The eyes are considerably more narrowed 

 above, obliquely flattened on the upper three-fifths, not 

 recessed below, subangulate behind. The occiput is 

 moderately thick though only very slightly developed 

 above and obliterated at the vertex. Pile of occiput 

 coarse, moderately long, dense and opaque with an 

 irregular patch of numerous weak bristles which begin 

 just above the middle but become more numerous near 

 the vertex and which become stouter and abundant be- 

 hind the vertex. The proboscis is quite short, stout, 

 subcylindrical, with bluntly tapered apex and high 

 medial ridge. The apex has stiff pile, the base scarcely 

 swollen and with very long hairs ventrally. The pro- 

 boscis is directed nearly straight downward. Palpus 

 clearly of two segments, but the basal segment rather 

 short, excavated, the second segment long, cylindroid, 

 subclavate, attenuate close to the apex and with nu- 



