ROBBER FLIES OF THE WORLD 



491 



Genus Polysarca Schiner 



FiGDEES 348, T06, 1424, 1433, 2229, 2230, 2354, 2468 



Polysarca Schiuer, Verb. Zool.-bot. Wien, voL 16, p. 674, 

 1866. Type of genus : Polysarca violacea Schiner, 1866, by 

 original designation. 



Strange flies of robust form and deep, blue or pur- 

 plish black coloration ; wings dark brown with purplish 

 reflections. They are of medium or large size and 

 wing is imusually broad basally. Both branches of the 

 tliird vein and the costa end well above the wing apex ; 

 the second submargmal cell is expanded both above and 

 below the third vein and this cell is narrowed distally ; 

 branches of fourth and fifth veins evanescent ; ambient 

 vein absent. Length 25 to 30 mm. 



Head, lateral aspect : Head longer than usual and the 

 eyes sti-ongly convex anteriorly. The face is quite 

 prominent, especially extensive below at the epistoma ; 

 the extension begins a short distance beneath the an- 

 tenna and continues gradually and regularly below ; as 

 a result of this forward extension the subepistoma is 

 long and oblique; the face alone is only gently and 

 shallowly convex ; sides of face adjacent to the eye some- 

 what flattened. The greatly swollen occiput is thick 

 throughout its length but especially through the mid- 

 dle ; bristles begm at the middle of the head ; the lower 

 seven elements are lateral in position and quite slender, 

 but near the posterior eye corners they become stout 

 and directed upward and consist of about 15 slightly 

 curved bristles; these are set in a doubled or trebled 

 row behind the vertex. Ventral occipital pile fine, long 

 and bushy. The proboscis is short but exceedingly 

 broad and dorsoventrally flattened; its apex is short 

 pilose, the base long pilose ventrally. Palpus large with 

 numerous, long, fiiie, black hairs. The antenna is at- 

 tached at the upper third of head and is as long as the 

 head. First two segments short. The third segment 

 is long oval, with a short style as long as the segment 

 but with no microsegment present; the third segment 

 bears a few minute setae above. First segment with a 

 few short bristly hairs, the second with a few setae. 



Head, anterior aspect: Face moderately wide, not 

 quite two-sevenths of the head width below the an- 

 tenna ; it is distinctly divergent below. The upper part 

 bears numerous, fine, long, black hairs directed for- 

 ward; the whole lower half of the gibbosity has nu- 

 merous, moderately long, stout, black bristles covering 

 a triangular area in the middle and extending as a 

 single row down the lateral border of the subejjistoma. 

 The front dorsally is wider than the face and bears nu- 

 merous, long, fine, bristly hairs; the vertex is scarcely 

 excavated, the ocellarium very small and low with nu- 

 merous, erect hairs. The anterior eye facets are at most 

 only slightly larger or only imperceptibly increased in 

 size. 



Thorax : The mesonotiun moderately high, abrapt in 

 front, only slightly convex from a lateral view but 



strongly convex from an anterior view ; it bears dense, 

 moderately long, fine pile over the entire surface and 

 has stout, black bristles as follows : hmnerus with none, 

 3 short notopleural, 6 or 7 long supraalar, 6 or 7 posta- 

 lar, the prescutellar area with a row of 3 on each side, 

 the scutellar margin with 6 pairs of rather short 

 bristles. Scutellum thick, convex with deep, impressed 

 rim, the disc of scutellum with abundant, long fine pile. 

 Mesopleuron with abundant, quite fine, long pile over 

 the entire posterior dorsal half. Pteropleuron with 

 additional pile; hypopleuron with pile and 3 long, 

 stout, black bristles but metapleuron with a dorsal band 

 of stiff pile only, long and fanlike. While these are per- 

 haps equivalent to weak bristles they are distinctly 

 less stout than others on the pleuron. Pronotum with 

 numerous, long, stout, black bristles. Metanotal slopes 

 without bristles but with a large, dense tuft of reddish 

 brown pile. Metasternal .slopes pilose; postmetacoxal 

 area membranous. Posterior basalare with a dense 

 patch of bristly hairs ; tegula with setae. 



Legs : Tlie hind femur is rather stout, but not swollen ; 

 it bears dense, fine, subappressed, dark pile, longer ven- 

 trally, with 2 stout, rather long, dorsal subapical 

 bristles and a row of 4 dorsolateral bristles ending near 

 the middle, and to which 1 or 2 additional elements 

 may be added immediately above ; ventrolateral margin 

 with 8 to 11 bristles which are rather long, oblique and 

 stout, and to which extra ones may be added; ventro- 

 medial margin with 6 or 7 slightly longer, black bristles. 

 Apex with stout, long, spinous, black bristles, which 

 consist of : 2 lateral, 2 dorsal, 2 short medial and 4 ven- 

 tral bristles. Middle femur with 7 or 8 anterior bristles 

 placed especially along the middle and with 2 dorso- 

 subapical and 1 anterior quite at the apex, and with 13 

 or 14 moderately long, oblique, anteroventral bristles, 

 besides 5 or 6 posteroventral elements. Apex with cir- 

 clet of about 10 short, stout bristles. Anterior femur 

 quite stout with only 6 black, ventral bristles. The 

 bristles of the tibia are short and consist of 7 dorsal, 8 

 anterodorsal, 9 posterior bristles; its apex with 2 an- 

 terior, 2 dorsal, 2 posterior and 4 or 5 ventral elements. 

 Claws thick, stout, sharp, strongly curved from the 

 base ; the pulvilli four-fifths the claw length ; the em- 

 podium long and stout at base. 



Wings : The wings are exceptionally broad and dai'k 

 brown with purple or blue reflections; the wings are 

 especially broad at the base. Both branches of the 

 third vein and the costa end well before the wing apex ; 

 base of second submarginal cell strongly expanded both 

 above and below the third vein and this cell narrowed 

 some distally ; branches of fourth and fifth veins evanes- 

 cent ; ambient vein absent ; alula quite large. 



Abdomen: The abdomen is relatively short, stout, 

 subcylindrical, the tergites shortened posteriorly. The 

 sides of the first tergite bear dense, long, stiff pile 

 among wliich pile are 2 or 3 quite weak bristles. Ter- 

 gites with abundant, subappressed pile, rather long on 



