578 



UNITED STATES NATIONAL MUSEUM BULLETIN 224 



Abdomen: The abdomen is moderately stout and 

 comparatively short but not as wide as the mesonotum. 

 The abdomen bears scanty, coarse, erect hairs and some 

 more or less appressed setae. Lateral margins of the 

 tergites anteriorly with scanty, erect haire and with 

 bristly, appressed hairs posteriorly. Sides of first seg- 

 ment with 5 long bristles and 3 shorter bristles extend- 

 ing inward. The not pilose, posterior margins of the 

 tergites are unusually extensive in the males and bear 

 anteriorly some rather conspicuous, mostly slender 

 bristles, weaker in females but stouter laterally in 

 males on the fourth and fifth segments. Sternites with 

 scattered, long, slender, bristly hairs, the posterior mar- 

 gins of the last two sternites with numerous, rather 

 conspicuous, though slender bristles. Males with eight 

 tergites, the eighth is quite linear in the middle but 

 more extensive laterally, the sixth and seventh are also 

 reduced in length in the middle. Females with eight 

 tergites, the seventh and eighth bearing conspicuous, 

 posterior bristles. Male terminalia quite large and con- 

 spicuous with the widely separated, superior forceps, 

 which are convex and curve medially inward apically; 

 these forceps tend to bear a subbasal process which 

 carries a dense fringe of stout bristles and with a 

 fringe of weaker bristles medially beyond. The hypan- 

 drium is rather long, wide and conspicuous; the gono- 

 pod is also conspicuous ; the aedeagus is prominent and 

 tubular. Female terminalia consist of a very short 

 ninth segment, wliich at the base is about half as wide 

 as the eighth segment. It is gently convex dorsally 

 and beyond it bears the smaller, medially divided, sub- 

 triangular tenth segment. Eighth sternite with a dense 

 patch of long, conspicuous bristles over its whole sur- 

 face. 



Distribution : Neotropical : Threnia carbonaria 

 Wiedemann (1828) ; helleri Carrera (1952) ; longipen- 

 nis Schiner (1868) ; higens Schiner (1868) ; rabeUoi 

 Carrera (1952). 



Oriental: Threnia acanthura Wulp (1898); micro- 

 telusWnlpilSQS). 



The oriental species described by Wulp probably 

 belong elsewhere. 



Genus Acanthopleura Engel 



Figures 361, 776, 1496, 1505, 2188, 2275, 2338, 2375 



Acanthopleura Engel, in Lindner, Die Fliegen der palaearkti- 

 schen Region, vol. 4, pt. 24, Asilidae, p. 67, 1927. Type of 

 genus : Asilus hrunnipes Fabricius, 1794, by original desig- 

 nation. 



Large flies characterized by the gibbous face, which 

 bears numerous, stout bristles that extend as far as the 

 upper third of the face. The mesonotum lias minute, 

 scanty, short setae but also a conspicuous, short row 

 of sharply delimited, long, stout, dorsocentral bristles 

 opposite the postalar area containing 5 or 6 elements. 

 The name is derived from the presence of a few bristles 

 along the dorsal margin of the mesopleuron. Other 

 pleural areas with bristles are the hypopleuron, which 



bears a vertical row of 3 or 4 long, stout bristles ; also 

 the notopleuron has numerous bristles and the meta- 

 notal callosity bears abundant, stiff, bristly pile. Hu- 

 merus without bristles. Length 30 mm. 



Head, lateral aspect : The face is moderately protu- 

 berant on the lower two-thirds, arising shallowly but 

 abruptly. Cheeks prominent. Eye long, strongly con- 

 vex anteriorly, nearly plane in the middle portion be- 

 hind ; rounded posterodorsally, it is sharply anteroven- 

 trally recessive on the lower fourth and also plane on 

 this portion. Occiput shoi-t : pile of occiput unusually 

 dense and long on the ventral half, becoming fine and 

 scanty and reduced to little more than 1 or 2 deep sub- 

 medial rows on the upper portion of occiput. In addi- 

 tion there is present on the occiput a conspicuous row 

 of dorsal, submarginal bristles, all rather short; the 

 upper group contains 12 stout, straight elements and 

 they are confined to the upper fourth of the head ; there 

 are approximately 12 other weaker bristles beginning 

 where the upper group ends and these are curved down- 

 ward. Proboscis moderately long, subcylindrical and 

 gently swollen toward the base both laterally and dor- 

 sally; it has a long, low, medial ridge. The apex is 

 bluntly rounded and bears a few, fine hairs apically and 

 especially ventrally ; base of proboscis below with nu- 

 merous, long, slender hairs. Palpus of one long, slen- 

 der, cylindrical segment ; it becomes a little more robust 

 distally and bears numerous stout, apical bristles. 



Head, anterior aspect : The face below antenna is a 

 little more than a fifth the head width and divergent 

 below. The subepistomal area is large, nearly plane, 

 pubescent, oblique and encroaching on the face. The 

 face is pubescent, the gibbous portion containing a 

 large number of stout, slightly curved bristles which 

 extend obliquely forward and downward; the more up- 

 per elements are nearly straight forward. Sides of the 

 oral margin with similar bristles; face without pile. 

 The antemia is attached at the upper tlurd of the head; 

 the first segment a little longer than the second and all 

 of the segments rather slender. The third segment is 

 as long as the first 2 combined, its style excepted; this 

 segment bears a small, short but distinct microsegment 

 and beyond it a rather thick, short, basally tliickened 

 and apically, slightly thickened style with minute, 

 apical spine. The style itself is thickened at apex; 

 and style and microsegment together are three-fourths 

 as long as the third segment. The first segment bears 

 numerous, short, stiff, bristly hairs dorsally and later- 

 ally and below, all subappressed and with 1 much 

 longer, ventral bristle. Second segment with only a 

 few short, bristly hairs above and below. The front is 

 pollinose with short, stiff pile along the eye margins; 

 the sides of the front are distinctly divergent in the 

 middle, convergent again at the vertex; the vertex is 

 deeply excavated, the ocellarium low, containing in the 

 middle 3 or 4 fine, short hairs and an additional pair 

 behind the ocelli. Postocellar area with deep, sub- 

 lateral, grooves. Anterior facets slightly enlarged. 



Thorax : The thorax is densely pollinose ; the pile of 

 the mesonotum is composed of comparatively numer- 



