MBGAPODINAE 



ROBBER FLIES OF THE WORLD 



423 



and oblique. The front is short, with longitudinal, de- 

 pressed groove on either side; it bears a dense patch of 

 bristles and bristly pile on either side diagonally from 

 the antenna. The front is slightly wider in the middle 

 than the upper face, the vertex strongly excavated, the 

 ocellarium large, the sides slanting and it bears a post- 

 ocellar tuft of short, coarse pile. Sides of the vertex 

 with a dense tuft of bristly pile. Anterior eye facets 

 only slightly enlarged. 



Thorax : The mesonotum is long and quite low, pol- 

 linose and partly feebly shining with scattered, fine, 

 bristly pile, none of it differentiated. The bristles of 

 the lateral margin are exceptionally weak and consist 

 of 1 notopleural, 1 or 2 still weaker supraalar, 8 to 10 

 postalar, and no scutellar marginal bristles. Scutellar 

 discs rather flattened, with a few scattered hairs. 

 Humerus densely pilose. Pleuron without bristles ex- 

 cept on the metapleuron where they are numerous but 

 weak. Pteropleuron as well as the upper sternopleuron 

 and almost the whole mesopleuron densely pilose, the 

 hairs coarse but very fine at the apices. "Whole of the 

 propleuron with similar pile. Prosternum dissociated. 

 Metasternum pilose ventrally and laterally. Postme- 

 tacoxal area narrowly membranous. Prosternum small 

 and fully dissociated. 



Legs: The femora are only moderately stout; the 

 hind femur, together with its tibia and basitarsus are 

 lengthened, the femur slightly enlarged distally. The 

 legs are unusually bare and shining, with quite scanty, 

 suberect, setate pile, almost absent on the hind femur. 

 All femora with a conspicuous, ventral fringe of rather 

 long, slender, attenuate, shining, basally stout bristles 

 and all remaining bristles very stout. The hind femur 

 has 4 lateral, 2 or 3 dorsal on the outer half and 7 

 or 8 shorter ventrolateral bristles besides a medial row 

 of 6 or 7 bristles. Middle femur with 5 prominent 

 posterior bristles and other slender elements, a like num- 

 ber of anterior bristles and sometimes additional lateral 

 bristles near the apex. On the anterior femur bristles 

 are fewer, 2 on either side near the apex. Hind tibia 

 with 3 dorsal, the basal element usually doubled, 4 

 lateral, and 1 ventral distal bristle. Middle tibia with 

 6 or 7 anterior, 3 or 4 scattered posterior dorsal bristles, 

 6 or 7 posteroventral bristles, and 4 stout ventral 

 bristles. Anterior tibial bristles rather similar, the ven- 

 tral brush of pile in ranks. Protibial apex with a very 

 long, stout process and attached, robust, stout spine. 

 Basitarsus with a thick, distally protruded flange. 

 Claws sharp, pulvilli and empodium well developed. 



Wings: The wings are dark brown with purplish 

 tinge. Marginal cell closed with a short stalk ; anterior 

 branch of the third vein strongly sigmoid. Fourth pos- 

 terior cell closed with a long stalk, the remaining cells 

 open, the first posterior cell narrowly open. Anal cell 

 closed with a short stalk. Alula large, the ambient 

 vein complete. 



Abdomen: The abdomen is at least as wide as the 

 mesonotum ; the pile is dense, appressed and setate, and 

 on the sides longer and erect on the first 2 tergites. 

 Males with seven tergites, the eighth totally concealed. 



Females with seven tergites, the eighth incorporated 

 in a large, triangular, gently convex ovipositor. Male 

 terminalia very large, cylindrical, the ninth segment 

 forming a fused ring. They are half rotate, the 

 epandrium is very large, broad, long and undivided, 

 the dorsal proctiger large, long, conspicuous and curved 

 upward, with a pair of prongs. Most of this process, 

 including the prongs, may consist of an extension of 

 the epandrium. The hypandrium or ventral portion 

 of the ninth segment short. The gonopod is large, 

 ventrally protruded into processes which meet distally, 

 leaving a large, triangular, exposed cavity to the 

 genitalia; it also has a shorter dorsal process. On the 

 females the ninth and tenth segments are very much 

 shorter and smaller than the eighth; the tenth bears 

 lateral lol)es, which, however, are not free. The eighth 

 tergite and sternite form a large, triangular, dorsoven- 

 trally flattened body with both upper and lower sur- 

 faces shallowly convex. 



Distribution: Neotropical: Pronomopsis chalybea 

 Hermann (1912) ; rubripes Hermann (1912). 



Genus Megapoda Macquart 



Figtjbes 247, 635, 1275, 1284, 1564, 1568, 1816, 2111, 2139 



Megapoda Macquart, Histoire naturelle des insectes, dipteres, 

 vol. 1, p. 288, 1834. Type of genus : Laphria labiata Fauri- 

 cius, 1805, as Megapoda cyanea Macquart, 1834, the only 

 included species. 



Large, remarkable flies rather readily characterized 

 by the extremely long, slender legs, with prominent 

 protibial protuberance and spine and basitarsal flange. 

 The wing is exceptionally long and slender. The ab- 

 domen is elongate and moderately slender with more or 

 less parallel sides. It is a little flattened basally, cylin- 

 droid, club-shaped distally. The type of the genus is 

 a dark blue black fly with a yellow, ventrally produced 

 face and bluish brown or blackish wings. The mes- 

 onotum is long, comparatively low, the third an- 

 temial segment long oval. The proboscis is quite long, 

 a little compressed laterally on the base and from the 

 lateral aspect rather strongly attenuate to a compara- 

 tively slender point. The outstretched length of the 

 anterior and posterior legs 65 to 70 mm. Length 28 

 mm. 



Head, lateral aspect: The face is prominent, espe- 

 cially below, somewhat triangular, the anterior margin 

 being straight. Eye slightly but distinctly wider be- 

 low, strongly flattened anteriorly. Occiput mostly 

 obliterated in profile, becoming very narrowly visible 

 on the lower fourth. The pile is scanty, fine and 

 bristly ; the bristles become a little more stout dorsally ; 

 those in the middle tend to be curved outwardly. The 

 proboscis is exceptionally long and slender and from 

 the lateral aspect distinctly attenuate beyond the base 

 and again near the apex, leaving the apox rather slen- 

 derly pointed and more or less cylindrical. The base 

 is somewhat compressed laterally. At the apex are a 

 few, fine, short, minute hairs and at the base a few, 



