508 



■UNITED STATES NATIONAL MUSEUM BULLETIN 224 



This genus is close to Asilus Linn§, 1758, from which it is 

 separated chiefly by the absence of pilosity on the lateral cal- 

 losities of the postscutellar region ("lateral slopes of the met- 

 anotum" of Curran) ; by the form of the proboscis, which is 

 not so thick at the base ; by the form of the genitalia ( S ) where 

 the ninth sternite is rather well developed; by the greater 

 length of the ovipositor. There is also some affinity between 

 EraxasUus n.gen., and Reyasilus Curran, 1931. However, the 

 original diagnosis of the latter indicates characters that are 

 not found in EraxasUus, such as the presence of more or less 

 conspicuous acrostichal bristles and the abundant pilosity of 

 the pteropleura. 



Length 17-19 mm. ; wing 11-12 mm. 

 Distribution : Neotropical : EraxasUus pruinosus Car- 

 rera (1959). 



Myaptex, new genus 



FiGUKES 195, 688, 1400, 1499, 2267, 2313, 2437, 2445 



Type of genus : Myaptex hermanni, new species. 



Medium size flies of dark coloration. The head is 

 nearly circular from the front and the face has a promi- 

 nent, abruptly developed gibbosity on the lower three- 

 fourths, which bears numerous, long, bristly hairs. 

 The antenna is attached only barely above the middle 

 of the head and the deeply excavated vertex has vertical 

 sides. Metanotum without pile, the tergites are with- 

 out lateral bristles, except on the first tergite. Myaptex 

 will trace to Regasilus Curran from which it differs 

 by the greatly narrowed, distal end of the discal cell, 

 the strong, facial gibbosity occupying the lower three- 

 fourths of the face, the curved occipital bristles. These 

 flies are possibly related to the Neolophonotus Engel 

 group. Length 15 mm. 



Head, lateral aspect : The face is very strongly pro- 

 duced on the lower tlu-ee-fourths and the gibbosity 

 abruptly developed. The eye ventrally is angular but 

 comparatively long. The occiput is well developed and 

 more prominent below, due to the recession of the eye ; 

 bristles begm above the middle and consist of 7 short, 

 weak, yellow bristles turned downward, and above 

 these, nearer the vertex, are 10 short but stout black 

 bristles on each side; pile of occiput fine, long, mod- 

 erately abundant and brownish white. The proboscis 

 comparatively short and robust, extending but little 

 beyond the facial gibbosity. At the apex it bears pile 

 only dorsally and the apex is obtusely rounded; ven- 

 trally it bears a tuft of long hairs which originate and 

 are restricted to the middle of the proboscis. The palpus 

 is small, cylindrical, slender, with stiff, long, yellowish 

 hairs. The antenna is attached a little above the middle 

 of the head, and style excepted, it is considerably shorter 

 than the head. The first segment is twice as long as 

 the second and the second segment scarcely longer 

 than wide; both bear short, bristly hairs below and 

 long, fine setae above. The tliird segment is as long as 

 the fii-st segment; it is long oval and wider than the 

 basal segments and it bears a distinct, short micro- 

 segment followed by a stout, oblique style very little 

 longer than tlie third segment ; the third segment may 

 have 1 or 2 fiine hairs above. 



Head, anterior aspect : The face beneath the antemia 

 is about a fourth the head width and slightly wider 

 below. The upper face is without pile, the whole face 

 with brownish white pubescence. The whole gibbosity 

 of the face bears numerous, long bristles. The bristles 

 wliich compose the lowest row across the epistoma are 

 quite stout, but the doi-sal elements and the greater part 

 of the bristles are slender; slender bristles continue 

 down the sides of the epistoma, the lateral elements are 

 brownish yellow, other bristles are black. The front is 

 large, with a single longitudinal row of 10 fine, long, 

 stiff or bristly hairs on each side. Vertex deeply ex- 

 cavated, with steep or vertical sides; the ocellarium is 

 small and low and bears on each side 4 rather stout, 

 long bristles. 



Thorax: The mesonotum is not high and is gently 

 convex in front with a double acrostical row of stiff, 

 short, black, suberect setae and with an adjacent bare 

 stripe followed by a row of 9 or 10 similar, dorsocentral 

 elements which become extremely long and very stout 

 before the middle of the mesonotum ; there are 3 bristles 

 posteriorly in the acrostical row. All lateral bristles 

 are black, long and stout, and consist of 2 notopleural, 

 2 postalar, and 2 scutellar bristles all directed upward. 

 The disc bears abundant, stiff, moderately long, curved, 

 upturned, yellow pile. Pleuron with a vertical row of 

 6 bristles on the metapleuron, the 2 lower elements 

 rather long and moderately stout ; and the metapleuron 

 with 4 or 5 additional, long, slender, yellow, erect 

 hairs. Propleuron with 3 pairs of rather long, mod- 

 erately stout, yellow bristles. Humerus with only yel- 

 low pile. Upper stemopleuron and postmesopleuron 

 below with 3 to 5 slender, yellow hairs, the stemopleu- 

 ron with 10, pteropleuron with 8 hairs. The metanotal 

 slopes are moderately bullose, slightly creased medially 

 and without pile, pubescent only. Lateral metastemiun 

 with a few weak hairs; postmetacoxal area mem- 

 branous. 



Legs : The anterior and middle coxae have nmnerous, 

 very stiff, brownish white, long, backwardly curved 

 haii-s. Hind femur distinctly stout, densely appressed, 

 short, brownish yellow setate with numerous, rather 

 long, stout bristles consisting of 4 lateral elements and 

 1 dorsomedial bristle and 1 dorsomedial apical bristle. 

 Along the anterior ventral margin are esjiecially stout, 

 long, black bristles; ventromedial margin with 9 or 10 

 long, slender, brownish white hairs, among which are 

 a pair of stiff, brownish yellow bristles close to the base. 

 The hind tibia is slender and has 4 stout, black bristles 

 dorsolaterally and 2 strong lateral bristles at the middle 

 and outer fourth; apex with 3 ventral and 1 lateral 

 bristle. Middle femur with 5 very stout, long, anterior 

 bristles and 5 anteroventral bristles and the postventral 

 margin with a row of 10 long, stiff, brownish yeUow 

 hairs or weak bristles. The middle tibia has moderately 

 long, stout bristles : 3 dorsal, 2 anterodorsal at the mid- 

 dle and outer fourth, 4 posterior, 2 of them near the 

 middle posteroventraUy, and 2 especially strong ob- 

 lique, long, ventral elements ; also at the outer fifth are 3 



