piSVrOfiONINAE 



ROBBER FLIES OP THE WORLD 



133 



widely scattered, long setae. The lateral complement 

 of bristles consists of no humeral, 2 long, stout noto- 

 pleural, 1 supraalar, and no postalar or scutellar 

 bristles. The scutellum is a little convex, with scattered 

 setate hairs on the basal half. The pronotum is un- 

 usually prominent and long, with wide shallow crease 

 or depression; the anterior collar has 5 or 6 pairs of 

 stout bristles; the posterolateral pronotum with 1 long 

 bristle and at least 12 slender, shorter bristles or bristly 

 hairs. Lateral cervical sclerites with numerous stout 

 and also slender bristles. Lateral prothorax with short 

 bristly hairs. Prostemum dissociated. Remainder of 

 pleuron bare, except for the metapleuron, which has 3 

 or 4 stout bristles and a few hairs. The lateral meta- 

 sternum is bristly pilose, the postmetacoxal area 

 membranous. 



Legs: The legs fine, appressed setate, the bristles few 

 in number. The hind femur and tibia rather distinctly 

 elongate; this femur bears 3 to 5 lateral bristles, 2 

 medial at the base, its tibia has 8 dorsomedial, 6 dorso- 

 lateral, 3 ventrolateral bristles, and the apex has only 



1 dorsal bristle, 1 lateral and 1 ventrolateral bristle. 

 Middle femur with 1 long ventral bristle near the base, 



2 posterodorsally near the apex, and 2 anteriorly at 

 basal and distal thirds. The bristles of this tibia con- 

 sist of 7 short dorsal, 7 anterodorsal, 5 posteroventral, 

 and 2 longer, basally stout, ventral bristles confined to 

 the outer half. The anterior legs similar to the middle 

 legs but the femur is without anterior bristles. An- 

 terior tibia without apical spine. All tarsi long and 

 slender, the basitarsal segment as long as the next three ; 

 pulvilli long; empodium quite fine but widened 

 laterally at the base and quite thin dorsoventrally. 



Wings: The wings are quite broad and almost uni- 

 formly dark brown. Marginal cell widely open, all the 

 posterior cells fully open, the anal cell widely open. 

 The middle end vein of the second basal cell is long; 

 both end veins of the discal cell of equal length, the 

 anterior crossvein enters the discal cell at or near the 

 middle. Alula short; ambient vein complete. 



Abdomen: In general appearance the abdomen is 

 slender, yet nearly as wide as the mesonotum ; it is sub- 

 cylindrical with parallel sides, and rather elongate. 

 Pile of abdomen abundant, yet fine, somewhat bristly 

 and subappressed, nowhere concealing the dully sinn- 

 ing, black ground color. Bristles restricted to the first 

 tergite with 5 or 6 lateral pairs. Males with seven 

 tergites and a short dorsal liplike trace of the eighth 

 segment, somewhat reduced in width. Terminalia 

 quite short, but wide, somewhat mammiform. Male 

 terminalia are rotate one-fourth. The epandrium has 

 a V-shaped cleft to its base, the proctiger is very 

 short and likewise cleft. Gonopod short, swollen 

 basally, attenuate at apex and the hypandrium ex- 

 tremely short. 



Distribution : Neotropical : Macrocolus barrettoi Car- 

 rera (1949) ; bicolor Engel (1930). 



Genus Dizonias Loew 



Figures 110, 471, 951, 960, 1770, 1773, 1927 



Dizonias Loew, Berliner Ent Zeitschr., vol. 10, p. 30, 1866. 

 Type of genus : Dizonias phoenicurus Loew, 1866, by mono- 



typy. 



Large flies characterized by the cylindroid, parallel- 

 sided abdomen, the long, slender, third antennal seg- 

 ment, and the numerous, stout bristles of the face. The 

 broad wings are dark brown or blackish. Dizonias is 

 one of a small group of interrelated New World genera, 

 each with few species and all noted for the abundance 

 of stout bristles on the legs and face. These genera 

 related to Dizonias are Sphageus Loew, Prolepsis Wal- 

 ker, Tolmerolestes Lynch Arribalzaga and Cylicomera 

 Lynch Arribalzaga. These could be confused only 

 with Osprwcerus Loew of the Stenopogon Loew group ; 

 this group has a circular head from the frontal aspect, 

 fewer face bristles, and males with terminalia not ro- 

 tate. Length 20 to 25 mm. 



Head, lateral aspect : The head is of moderate length. 

 The face is prominent but nowhere greatly extended or 

 gibbous; face shortest on the upper fifth beneath the 

 antenna and at this point its rises or extends gradually 

 and the remainder of the face is almost plane. The 

 occiput is prominent especially on the dorsomedial por- 

 tion, sloping gradually away from the eye margin. 

 Pile of the occiput coarse and abundant and largely 

 restricted to the ventral third with a few medial hairs 

 on the upper part near the foramen. Laterally, begin- 

 ning below the middle of the head are several rows of 

 submarginal bristles ; those upon the upper half nearest 

 the eye margin are especially stout. The proboscis is 

 prominent, extended well beyond the face and held not 

 quite horizontally ; beginning near the basal third, the 

 proboscis tapers gradually towards the apex so that 

 the latter is comparatively narrow and bluntly rounded 

 with numerous apical, coarse, bristly hairs; the base 

 on either side has a number of long, slender, bristly 

 hairs. Palpus clearly of two segments, the first seg- 

 ment hemicylindrical and excavated, the second spindle- 

 shaped, sometimes attenuate at the apex, with large 

 apical pore, and always with exceptionally coarse, stout 

 bristles. The antenna is attached at the upper fifth of 

 the head and is always elongate; it is distinctly longer 

 than the head. The third segment is much the longest 

 and two to three times as long as the combined remain- 

 ing segments. First two segments each with 4 or 5 

 stiff, ventral bristles; the third comparatively slender, 

 slightly widened, gradually through the middle, with- 

 out microsegment and the apex obliquely open and 

 spoon-shaped with concealed interior spine. 



Head, anterior aspect : The head is distinctly though 

 only moderately wider than high, the face is wide and 

 at the antenna it is slightly more than one-fourth the 

 head width and divergent below to nearly one-third 

 the head width. The face is pale micropubescent 

 laterally, the broad medial portion shining and bare 

 and rather thickly beset with unusually stout, long, 



