DASTPOGONINAB 



ROBBER FLIES OF THE WORLD 



277 



bristles nearly absent or greatly reduced. Head and 

 abdomen drooping. The protibial process is short and 

 its spine often twisted. The abdomen is cylindroid, 

 at most slightly tapered and the antenna approximately 

 as long as the head. The species of this genus tend to 

 be comparatively variable and the sexes may be some- 

 times of greatly different color. Length 10 to 20 mm. 



Head, lateral aspect : The head is of medium length, 

 with the face short and usually plane; more rarely 

 there is a transverse depression below the middle, and 

 sometimes the face is very gently convex. The occiput 

 is never prominent, except below where there may be 

 a moderate anteroventral recession of the eye. Oc- 

 cipital pile stiff, loose and scattered, with weakly devel- 

 oped bristles beginning at the midplane of the occiput. 

 The proboscis is prominent, extending well beyond the 

 face, with high medial ridge disappearing apically. 

 The apex is rather sharply pointed and bears fine bris- 

 tles or pile ; base and sides below with numerous, long, 

 bristly hairs. Palpus clearly of two segments; the 

 first segment is excavated, the second spindlelike with 

 apical pore and numerous bristly hairs. The antenna 

 is elongate and attached at the upper fourth of the 

 head ; usually of the same length of the head, but may 

 be a little longer, the third segment is of the same or 

 slightly greater length than the combined first two seg- 

 ments with short or long obliquely truncate, spine- 

 tipped microsegment. The third segment may be 

 scarcely wider than the second, or it may be widened 

 in the middle or throughout its length; dorsal bristles 

 absent. 



Head, anterior aspect : The face is densely pubescent ; 

 usually without pile or bristles on the upper two-thirds 

 of face, and such elements are often confined to the 

 narrow, supraepistomal border. The face is wide, 

 from a fourth to two-fifths the head width, the front 

 is slightly wider than the upper face, pollinose, with 

 scattered, fine, bristly hairs on either side and the ver- 

 tex shallowly to moderately excavated with low, broad, 

 ocellar protuberance bearing 2 or 3 pairs of bristles. 

 The central anterior eye facets are moderately enlarged. 



Thorax : The mesonotum is generally bare in appear- 

 ance; the pile is restricted to rather minute, scat- 

 tered, appressed, bristly setae and sometimes longer 

 hairs along the lateral margin. The mesonotum is low, 

 at most gently arched, often pollinose and bears the 

 following complement of bristles: no humeral, 2 or 

 3 notopleural, 1 or 2 supraalar, 2 postalar, and 1 to 4 

 pairs of scutellar bristles. The pronotum bears stout 

 bristles; the postpronotum is quite prominent, sepa- 

 rated from the anterior portion by a deep crease, and 

 usually bears several stout, lateral bristles, but some- 

 times only a tuft of bristly hair. The pleuron may be 

 quite bare or thinly or densely pubescent. Mesopleu- 

 ron, pteropleuron, and hypopleuron without pile; the 

 metapleuron has a vertical row or band of moderately 

 stout bristles. Presternum dissociated. Metanotal 

 callosity without pile or bristles. Postmetacoxal area 

 membranous. Lateral metastemum with pile. 



Legs : The hind femur is stout without being swollen ; 

 its pile consists of rather dense, fine, subappressed 

 setae, the bristles reduced to few or none; rather char- 

 acteristically there is a stout, lateral bristle at the basal 

 third ; this tibia bears quite stout, rather short bristles, 

 2 to 5 dorsomedial, 4 to 6 dorsolateral, 3 to 6 ventro- 

 lateral bristles. The apex has 8 to 10 bristles, all 

 but one of which are ventral. Anterior and middle 

 femur with similar short setae and with a single stout, 

 posterior bristle near the apex. Anterior and middle 

 tibiae each with anterodorsal, posterodorsal, postero- 

 ventral, and ventral bristle rows, the middle tibia also 

 has a row of short anteroventral bristles; all these bris- 

 tles are short and stout except the longer ventral 

 elements, the first of which is attached at the middle; 

 the pile is scanty or absent but line, appressed setae 

 are commonly present. The apex of the anterior tibia 

 usually has a short protuberance, rarely extended be- 

 yond the apex and bearing a stout, sometimes twisted 

 spine. Base of basitarsus with a few denticles; claws 

 sharp; pulvilli fully developed; empodium flattened. 



Wings : The wings are generally broad, the marginal 

 cell and all of the posterior cells widely open except 

 the fourth, which is open but sometimes narrowed. 

 Anal cell usually wide open, rarely closed in the mar- 

 gin. Alula present ; ambient vein complete. 



Abdomen: The abdomen is generally cylindroid, 

 occasionally flattened across the middles of the tergites. 

 Sides either nearly parallel or only slightly tapered. 

 Males with eight tergites, the eighth quite short. Fe- 

 males with the eighth tergite approximately half as 

 long as the seventh. Pile of abdomen scanty, short, 

 fine, setate and appressed, giving these flies quite a bare 

 appearance. Bristles restricted usually to the first ter- 

 gite where there are 2 to 6 stout pairs laterally. Sec- 

 ond tergite quite uncommonly with 1 or 2 bristles. 

 Male terminalia with convex, conical, undivided epan- 

 drium or the latter broad, shieldlike, apically cleft 

 or fully cleft and overlapping, but never with well 

 developed or pronglike superior forceps ; the condition 

 varies according to the subgenera. Female terminalia 

 with a circlet of spines upon the acanthophorites. 



Saropogon has a nearly world wide distribution. 

 Some of the species show minor differences, but since 

 they are principally associated with the male terminalia 

 and since no correlating differences have been found for 

 females, it is difficult to see how these distinctions, such 

 as for Araiopogon Carrera, can rank as more than sub- 

 genera. There are quite a few species in New Zealand. 

 The genus is most abundant in North Africa, southern 

 and central Europe, but is not rare in the United States. 



Distribution : Nearctic : Saropogon dboreviatus John- 

 son (1903) [ = bicolor Johnson (1903)] ; aridus Curran 

 (1930) ; birdi Curran (1931) ; comhustus Loew (1874) 

 [ = adustus Loew (1874)]; coauillettu Back (1909); 

 dispar Coquillett (1902) ; fietcheri Bromley (1934) ; 

 hyalinus Coquillett (1904) ; laparoides Bromley 

 (1951); luteus Coquillett (1904) [ = rufus Back 

 (1904)]; pritchardi Bromley (1934); purus Curran 



