LAPHRIINAB 



ROBBER FLIES OF THE WORLD 



369 



ranging from 1 to 2 on the basal tergites to as many 

 as 3 or 4 in other species. Male terminalia large and 

 conspicuous, rotate one-half, with the lower portion 

 expansive and bulblike. Female terminalia quite short 

 with minute slender posterior lobes. 



Distribution: Palaearctic: Stiphrolamyra albibarbis 

 Engel_(1928); rubicunda Oldroyd (1947). 



Ethiopian: Stiphrolamyra angularis Loew (1858); 

 bipunctata Loew (1858) ; comans Hobby (1939) ; diax- 

 antha Hermaim (1907) ; rubra Bromley (1935). 



Tribe Atomosini 



This tribe contains small, often abundant, dominant 

 asilids of compact form and rather bare aspect. Al- 

 most world-wide in distribution, they appear to be 

 scarce except in the Neotropical region, from which 

 many genera are known. They are readily distin- 

 guished from all other Laphriinae, except 1 or 2 species 

 of Proagonistes Loew, which are very large asilids, 

 long in the legs, by the presence of a complete arch 

 of chitin behind the posterior coxae. The lateral cal- 

 losity of the metanotum appears to be without ex- 

 ception bristly but this is not an exclusive character 

 within the subfamily, since there are at least 4 genera 

 of Laphriini and 6 of Andrenosomini which likewise 

 have such bristles. In those members of the genus 

 Proagonistes with chitinized metasternum, there is a 

 medial seam. 



Two nearly equal groups may be separated, somewhat 

 artificially perhaps, on the presence or absence of the 



subapical spine, or spinous bristle situated on the third 

 antennal segment. Such a bristle is characteristic and 

 often accompanied by a distinct excision in a number 

 of genera; in rare instances it is so small that it will 

 be detected with difficulty. The proboscis in this tribe 

 tends to be short, sometimes even shorter than the face, 

 small, cylindrical and truncate. In one small group 

 the antenna is greatly lengthened ; both first and third 

 segments are lengthened, while the intermediate seg- 

 ment is reduced or even beadlike. This group includes 

 Cerotainia Schiner, Cyphotomyia Williston, Bathrop- 

 sis Hermann, and Protichisma Hermann. Three 

 genera have the posterior cells reduced to four. The 

 ventral prosternum is fully chitinized. 



The adults like to rest on foliage in the sun and are 

 even more frequently found on the bark of logs or the 

 trunks of trees. Near human dwellings they often se- 

 lect the sides of outbuildings for watching posts. 

 Larval habits are unknown. 



KEY TO GENERA OF ATOMOSINI 



1. Third antennal segment with a dorsal or subdorsal spine, 



sometimes found with difficulty, usually placed at or but 

 little beyond the middle of the segment and with or with- 

 out an accompanying excision but not arising at or close 



to the apex of this segment 2 



No differentiated dorsal spine present on the third antennal 

 segment unless at or almost at the apex. Third segment 

 with or without a microsegment 24 



2. Third antennal segment with a dorsal spine and the post 



metacoxal area membranous. Tergal bristles prom- 

 inent Paratbactia, new genus 



Third segment with dorsal spine and postnietacoxal area 

 always with complete arch of chitin 3 



3. Four posterior ceUs only 4 



Five posterior cells present 5 



4. Third posterior cell eliminated and the fourth posterior 



cell closed and stalked Atomosiella Wilcox 



Third posterior cell eliminated and the fourth posterior 

 cell widely open Opocapsis Hull 



5. Antenna exceptionally long and slender, at least 2 times 



the head length. First and third antennal segments 

 share equally or nearly equally in the extent of 

 elongation, the second segment remaining quite short and 

 beadlike and the first segment unusually slender. Dorsal 

 spine of third segment usually poorly differentiated and 

 obscure and excision lacking. Face distinctly divergent 

 from the base below to the vertex ; posterior vertex exca- 

 vated and flared 6 



Antenna 1 to 2y 2 times the head length, or shorter ; first and 

 third antennal segments not of equal length ; dorsal spine 

 and excision well developed. Face width ranging from 

 normal to very narrow ; the vertex is at most moderately 



widened or maybe even narrowed ; postvertex usually only 

 moderately flared and excavated 9 



6. Face, beginning at epistoma, and vertex only gently widened. 



Lateral wall of vertex vertical. Upper occipital bristles 

 spinous. At least mesonotum and scutellum coarsely 

 punctured. Scutellar margin without bristles. Abdomen 

 slightly or moderately narrowed basally. 



Protichisma Hermann 

 Face and vertex strongly widened; lateral wall of vertex 

 slanting. Abdomen with parallel sides or narrowed pos- 

 teriorly 7 



7. Posterior margin of scutellum with a row of long, slender 



bristles Cerotainia Schiner 



Posterior margin of scutellum with only 5 short, erect, 

 stiffened hairs 8 



8. Grossly punctate flies, bare, with pile reduced to micro- 



scopic, scattered setae; occiput bare except for 4 stout, 

 laterally placed spines or spinous bristles. Anterior 

 mesonotum prolonged into a conspicuous, rounded, lat- 

 erally constricted hump Cyphotomyia Williston 



Without exceptionally deep or conspicuous surface punc- 

 tation; pile abundant, scattered, long and fine; oc- 

 cipital bristles moderately strong, weak or absent alto- 

 gether Cerotainia Schiner 



9. Face quite plane and high. Lower face considerably wider 



than upper face. Mystax and facial pile consists of long, 

 coarse hairs. End of third antennal segment unmodified. 

 Hind femur with a conspicuous row of quite long, rather 

 stout ventromedial bristles, especially towards the base. 

 Coarse punctures present on abdomen but not on thorax. 

 Lateral tergal bristles strong and conspicuous. Wings 

 beautifully banded 10 



