ROBBER FLIES OF THE WORLD 



567 



and bristles begin below the middle ; these bristles are 

 stout, the middle group is turned down, the upper group 

 shorter and nearly straight but with dense, rather fine, 

 long pile broadly behind the vertex. The proboscis 

 is blunt at apex, more or less cylindrical but appearing 

 compressed because of a rather high carina along the 

 middle. Palpus small, slender, with weak bristles. An- 

 tenna attached a little below the upper third of the 

 head and as long as the head; the first two segments 

 are slender and rather long, the first segment bears a 

 number of long, ventral, bristly hairs and sometimes 2 

 or 3 equally long, stout bristles. It has also lateral and 

 dorsal, long, bristly hairs. The third segment is rather 

 slender, a little widened in the middle, nearly or quite 

 as long as the first two segments; microsegment is 

 present and a short, stout, spine-tipped style, usually 

 not as long as the second antennal segment. 



Head, anterior aspect : The face below the antenna is 

 less than a fifth the head width and strongly divergent 

 below and micropubescent. The gibbosity has numer- 

 ous, medial, slender and sometimes stout bristles or also 

 bristly hairs ; all of the elements are long and extended 

 in several rows almost the full lateral margin of the 

 long, oblique, deeply concave subepistomal area. The 

 front is moderately enlarged, pubescent, with a subocu- 

 lar row of bristly hairs and 2 upper bristles nearer the 

 eye. It has nearly parallel sides and the vertex is only 

 a little excavated with slanting sides; the large, low 

 anterior ocellarium bears 3 or 4 pairs of central bristles 

 and as many as 5 postocellar bristles. 



Thorax : The mesonotum is rather high, sloping pos- 

 teriorly and abrupt anteriorly ; it bears quite scattered, 

 erect, bristly or setate pile with the surface pollinose. 

 There is a wide band of differentiated, dense, bristly 

 acrostical elements with a nearly bare stripe on each 

 side, continued anteriorly down the declivity. Slender, 

 anterior dorsocentral elements become longer at the 

 level just behind the humerus and generally remain 

 slender and more nimaerous in front of the scutellum. 

 Humerus bristly pilose; the notopleural area behind 

 the humerus has as many as 4 very long, slender, bristly 

 hairs ; the lateral complement of stout bristles contains 

 1 posthumeral, as many as 4 notopleural, 4 or 5 supra- 

 alar, 2 suprapostalar, 4 postalar, and 3 or 4 pairs of 

 scutellar bristles. Scutellum moderately thick, convex, 

 with impressed rim, pollinose and with dense, long, 

 stiff, discal hairs. Metanotal callosity bullose with 

 long, bristly pile. Pronotimi with bristles. The pro- 

 pleuron, upper and posterior mesopleuron, upper ster- 

 nopleuron and pteropleuron each with tufts of pile. 

 Posthypopleuron and metapleuron with vertical row 

 or band of long, stout bristles. Prosternum dissociated. 

 Postmetacoxal area membranous. 



Legs : The femora are stout, the tibiae somewhat less 

 so. First four femora distinctly swollen toward the 

 base ; these and the tibiae bear dense, appressed, coarse, 

 setate pile. Bristles are unusually stout and numerous, 

 except on the anterior femur. Hind femur with 5 or 

 6 dorsolateral, 9 ventrolateral, a few ventromedial and 

 an apical, oblique, lateral row of 7 bristles continued on 



the opposite side as 5 bristles, Middle femur with 4 an- 

 terodorsal, as many as 7 anteroventral and 2 bristles 

 at the apex posteriorly. Anterior femur with only an 

 anterior, apical row of 5 bristles. Hind tibia with 5 or 

 6 dorsolateral, 3 or 4 dorsal and 3 dorsomedial bristles 

 on the basal half, besides 4 or 5 ventrolateral bristles 

 over the middle portion. Apex with only 6 or 7 bristles. 

 Anterior 4 tibiae with rather similar bristle content and 

 the posteroventral elements tend to be longer. Basi- 

 tarsus as long as the next two segments. Bristles of the 

 first two or three segments pronounced. Claws long, 

 rather slender, sharp, bent at apex; the pulvilli and 

 empodium large. 



Wings: The marginal cell in the male slightly ex- 

 panded at the expense of the subcostal cell and closed 

 and petiolate. The third vein forks beyond the pos- 

 terior crossvein and the base of the second posterior 

 cell is only slightly widened. Wing faintly rippled. 

 Fourth posterior cell and anal cell closed and stalked. 

 Alula large; ambient vein complete. 



Abdomen: The abdomen is rather shorter and gen- 

 erally more robust than Machimus Loew or Eutolinus 

 Loew; it is subcylindrical and slightly tapered. The 

 submarginal, postlateral bristles of the tergites are ex- 

 ceptionally prominent and numerous with 4 or 5 pairs 

 on all tergites except the last two. The pile is subap- 

 pressed, coarsely setate; sternites bear long, slender 

 bristles which are nirmerous; the surface is pollinose. 

 There tends to be mats of somewhat divergent hairs in 

 the middle of the first several tergites. Males have 

 eight tergites of gradually decreasing length; the 

 eighth is almost concealed medially and very short 

 laterally. Females with only seven, the remainder 

 forming the ovipositor. The male terminalia is moder- 

 ately large, with long, erect proctiger, very short gono- 

 pod and in the type of genus the hypandrimn is con- 

 cealed or absent ; the eighth sternite is extremely short 

 and unmodified. Female terminalia remarkably com- 

 pressed laterally ; tlie ninth tergite is about half as long 

 as the eighth; the dorsal proctiger is flattened and 

 wedged in. The whole outer half is coarsely micro- 

 setate and sometimes micropunctate to a more pro- 

 nounced extent than in Eutolmxis. 



Distribution: Neotropical: Dysmachus americanus 

 Macquart (1846) ; strigitibia Curran (1931). 



Palaearctic: Dysmachus alMciJiatus Loew (1854); 

 alhiseta Becker (1907) ; albisefosus Macquart (1850) ; 

 albovestittis Villeneuve (1930) ; appendicuJaius 

 Schiner (1867); atripes Loew (1871); hasalis Loew 

 (1848); hi furcus Ijoew (1848) [=1nigripes Megerle, 

 Ms., in Meigen (1820), varius Meigen (1820), pertur- 

 bans Becker (1923)] ; iilobus Loew (1871) ; himucrona- 

 tus Loew (1854) ; cepJialenus Loew (1871), cephalenus 

 hidentatus Becker (1923) ; cochleatus Loew (1854) ; 

 cristatus Wiedemann in Meigen (1820) \^ = acutus 

 Ijoew (1870)]; dasynotvs Loew (1871); dasyproctus 

 Loew (1871) ; decipiens Wiedemaim (1820) [=multi- 

 color Scliiner (1854), variegatus Meigen (1830), vari- 

 spinus Strobl (1909)] ; digitidus Becker (1923) ; fdomi- 

 tor Meigen (1830) ; elapsus Villeneuve (1933) ; evanea- 



