DASYP0G0N1XAE 



ROBBER FLIES OF THE WORLD 



195 



bined, gradually and slightly dilated in the middle and 

 bearing a single rather long, attenuate, spine-tipped 

 niicrosegment. The attaclunent of this microsegment 

 is only slightly oblique. 



Head, anterior aspect : The face is wholly micropu- 

 bescent, moderately wide, about one- fourth the head 

 width and slightly divergent below. The front boars 

 a few short hairs. Ocellar protuberance prominent 

 but low, with numerous, long, fine hairs. Vertex very 

 shallowly excavated. 



Thorax: The mesonotum is comparatively convex, 

 moderately high, steeply arched in front and pollinose; 

 the pile is long, suberect and whitish. The mesonotum 

 is characterized by the presence of a row of long, fine, 

 backwardly curved acrostical bristles and a row of 

 quite long, fine dorsocentral bristles beginning near the 

 anterior margin and becoming slightly longer in front 

 of the scutellum. These bristles are almost as long as 

 those situated on the lateral margins. Humerus with 

 long, fine pile; long, lateral bristles are present as fol- 

 lows: notopleuron with 5, supraalar with 2, postalar 

 with 2 or 3, scutellar margin with 3 pairs which are 

 long, slightly curved upward, and tending to be con- 

 vergent. Collar with a few weak bristles and some pile, 

 both of same length. Mesopleuron with only long, yel- 

 low pile dorsally and posteriorly; propleuron pilose; 

 pteropleuron micropubescent only ; metapleuron with a 

 dorsal band of some long pile and 5 or 6 extremely 

 weak, yellowish white bristles. Hypopleuron with a 

 few long hairs. Metanotal slopes convex and micropu- 

 bescent only. Postmetacoxal area membranous. 

 Metasternal slopes laterally pilose. 



Legs: The anterior and middle coxa with long, 

 bushy, whitish pile anterolaterally ; postcoxa pilose lat- 

 erally. Hind femur distinctly longer than middle fe- 

 mur, moderately slender with long, appressed, yellowish 

 white pile above and dorsolaterally ; ventral surface 

 with abundant, long, yellowish white pile, longer on 

 the basal half and with 8 or 9 long, antero ventral, 

 yellowish white bristles and an equal number of ventro- 

 medial bristles. The lateral bristles consist of 1 in the 

 middle, 1 just beyond the middle, 1 near the outer 

 third, and 2 very weak dorsoapical bristles scarcely 

 stronger than the surrounding hairs. Tibia slender, 

 with a slightly enlarged apex. The hind tibia has 6 

 dorsal, 5 lateral, 6 ventral bristles; its apex has long, 

 yellowish white bristles, 2 lateral, 4 ventral, 2 dorsal 

 and medial. Middle femur with long, erect pile below, 

 appressed pile above and a weak subapical anterior 

 bristle. Its tibia has long, yellowish white, rather 

 stout bristles, 3 ventrals more or less posterior, all 

 equally long and some long anteroventral pile; .also 

 this tibia bears some unusually long dorsal bristles, 

 consisting of 5 anterodorsal and 5 posterior. Anterior 

 femur with long, whitish pile posteriorly and ventrally, 

 shorter posterior dorsal pile and shorter appressed 

 pile anteriorly and dorsally. Anterior tibia with a 

 double row of divergent, dorsal bristles, 5 in each row, 

 and 5 longer posterior, and 3 or 4 long, ventral bristles. 

 The apex of the anterior tibia bears 9 bristles and 



no terminal spine. Tarsi relatively slender with long, 

 apical bristles; basitarsus with 1 small posterior bristle. 

 Claws long, divergent, sharp and gently curved 

 throughout. Pulvilli absent. Empodium two-thirds 

 as long as claw, strongly thickened at the immediate 

 base. 



Wings: The marginal cell and all of the posterior 

 cells are widely open; anal cell open. Ambient vein 

 complete; alula narrow but convex. 



Abdomen: The abdomen is nearly as wide as the 

 thorax and fully as wide as the mesonotum ; it is slightly 

 convex on the first four or five tergites and all the 

 sides are narrowly rolled. The abdomen is progres- 

 sively narrowed from the end of the second tergite; 

 it is wholly greyish yellow pollinose, except basally on 

 the fifth and sixth tergites and the whole of the seventh 

 and eighth tergites. Pile is short, fine, erect and deli- 

 cate, longer along the lateral margins for the first four 

 tergites and in tufts along the sides of these. In the 

 female there are eight tergites, the eighth is about half 

 as long as the seventh, both of them shining black, 

 the others pollinose as described. Sublateral posterior 

 border of the first tergite with 3 or 4 extremely weak 

 bristles scarcely thicker than the surrounding hairs. 

 Female terminalia quite short with a hemicirclet of 

 4 or 5 pairs of short, orange brown spines laterally, 

 slightly protruded. Ventral plates divided and paired 

 but short. 



Distribution: Palaearctic: Mecynopus pulverulentus 

 Engel (1925). 



Genus Hystrichopogon Hermann 



Fiqukes 138, 569, 984, 993, 1765, 1767 



Hystrichopogon Hermann, Berliner Ent. Zeitschr., vol. 50, p. 26, 

 1905. Type of genus: Hystrichopogon hirticcps Hermann, 

 1905, by original designation. 



These are comparatively large flies with rather dense, 

 fine pile. They have a rather hump-backed appear- 

 ance because of the convex mesonotum and low-set head. 

 The abdomen is stout but elongate. Face convex and 

 produced with a subantennal crease and the eye com- 

 paratively small. Antenna unusually elongate, all seg- 

 ments lengthened and of nearly the same thickness ; the 

 third segment bears a dorsally short, ventrally extended 

 microsegment and enclosed spine. Length 17 mm. 



Head, lateral aspect: The head is comparatively 

 long. Both the eyes and face are strongly produced 

 and rounded. The face is strongly produced and con- 

 vex. A short distance below the antenna the face is 

 abruptly creased so that at this point it scarcely ex- 

 tends beyond the eye. The face descends well below 

 the eyes, the lower one-fourth without pile. The an- 

 tenna is set on a low protuberance and situated at 

 the upper one-eighth of the head. The occiput in pro- 

 file is swollen, thick and well developed except near 

 the upper eye corner. Occipital pile chiefly yellow, 

 the upper half of the occiput with 8 to 10 rather slen- 

 der, moderately long, black, strongly proclinate bristles. 



