I.AFHRIINAE 



ROBBER FLIES OF THE WORLD 



401 



this genus, and agree with Arribalzaga's description as 

 I interpret it. These 2 specimens bear the labels: 

 "Buenos Aires, Atomosia ? sp. no. 204, of Bigot col- 

 lection." The other bears a label in handwriting : "Ar- 

 ribalzaga, Atomositia, g. et sp. nov. (Chaeab. IX, 

 1880)." It was 2 years later that Lynch Arribalzaga 

 erected the genus Rhathhnomyia. 



Genus Lamprozona Loew 



Figures 244, G70, 1308, 1317, 2172 



Lamprozona Loew, Bemerkungen iiber die Faiuilie Asiliden, 

 1851, p. 18, 1S51. Type of genus: Lamprozona auricineta 

 Loew, 1851, by monotypy. 



Quite small, robust, compact flies that resemble Ato- 

 mosia Macquart but are without a dorsal spine-bearing 

 incision before the apex of the third antennal segment. 

 They are blackish flies and the end vein of the discal 

 cell and the fourth posterior cell are quite in alignment. 

 The whole face is rather densely covered with fine 

 bristles and the bristles of the front and vertex are 

 numerous and prominent. Length 7 mm. 



Head, lateral aspect : The face is almost wholly plane 

 with the eye, in profile there is a thin line visible on the 

 dorsal two-thirds and a short, rounded elevation below 

 due to the recession of the eye, leaving the face slightly 

 concave above. The eye is of moderate length, con- 

 siderably narrowed below ; most of it is due to a prom- 

 inent, gradual, posterior, anteroventral recession of the 

 eye which begins at the upper third of the head, leav- 

 ing most of the eye behind plane and strongly convex 

 on the upper third ; the occiput obliterated on the up- 

 per third, comparatively short at the lowest portion of 

 the eye but exceptionally thick and extensive over the 

 greater middle part. The proboscis is extremely short, 

 quite bluntly truncate apically and not extending be- 

 yond the face. The apical pile is directed outwardly 

 as a circular fringe ; middle of proboscis slightly con- 

 stricted, the whole cylindrical and not swollen ; the dor- 

 sal ridge absent or nearly so ; the base ventrally has a 

 transverse row of 3 pairs of long, slender, pale bristly 

 hairs; the whole structure is directed horizontally for- 

 ward. Palpus minute. The antenna is attached at the 

 upper fifth of the head, of moderate length : the first 

 segment is iy 2 times longer than the second, the third 

 segment not quite twice as long as the first two com- 

 bined; at the immediate base it is less wide than the 

 second segment ; for the greater part of its length it is 

 of nearly the same width and with nearly parallel sides ; 

 it is slightly tapered distally and ends in a quite sharp 

 point with minute apical spine ; it is cut away or exca- 

 vated dorsally near the apex; and at the base of the 

 dorsal excavation there is a distinct, larger, bristly 

 spine. The first and second segments are unusually 

 densely beset with stiff, comparatively long, black 

 bristles on all sides except medially ; there are at least 

 40 on the first and 5 or 6 ventrally and as many dorsally 

 on the second. 



Head, anterior aspect: The head is not very wide. 

 The face below antenna less than a fourth the head 

 width and with parallel sides. The subepistomal area 

 is comparatively small, oblique, concave and bare. Face 

 micropubescent on the lower half and narrowly along 

 the eye margin, with dark pollen between. Face apilose 

 but densely beset with bristles in two groups on the 

 very slight lv raised upper half of the face. There are 

 about 14 bristles on each side set in groups of 2 or •".. 

 On the lower, slightly convex, half of the face an- 40 

 or more bristles in irregular rows. Front short with 

 exceptionally numerous and quite long, rather stiff 

 bristles on each lateral fourth. The front is divided on 

 each side by a deep crease continued on each side of 

 the ocellarium. Vertex deeply excavated with rather 

 steeply slanted sides; the oceilarium large, high, and 

 with nearly vertical sides, and bearing 3 pairs of long, 

 slender, black bristles closely adjacent between the 

 ocelli and a more slender pair behind the ocelli at the 

 peak of the eminence. Anterior eye facets strongly 

 enlarged. 



Thorax: The thorax is shining, with very little pol- 

 len or pubescence; this restricted to the lower half of 

 the thorax although the mesopleuron is in some lights 

 very thinly pollinose and all of the pubescence is ex- 

 ceptionally minute. Pile of mesonotum rather dense 

 and unusually long, but bristly and without differen- 

 tiated acrostical or dorsocentral elements, although the 

 pile becomes a little longer generally over the posterior 

 half of the mesonotum. Humerus densely long, bristly 

 pilose. The following complement of quite long, bristly 

 hairs is present on the mesonotum: 1 notopleural, a 

 close-set, backwardly curved row of 3 supraalar set 

 quite low along the margin and almost immediately 

 above the wing, this row continued posteriorly with 

 more slender elements, 1 long postalar, and 4 pairs of 

 exceptionally long, delicate, scutellar bristles. Scutel- 

 lum a little thickened, slightly convex, with a quite 

 distinct impressed rim ; the basal crease is deep and the 

 disc with some short, bristly pile. 



Propleuron including the pronotum, with rather 

 scanty, bristly pile. Posterolateral pronotum densely 

 long, bristly pilose; bristles absent. Upper half of the 

 mesopleuron with numerous, long, bristly hairs. Pos- 

 terior margin of the mesopleuron just below the wing 

 with a single, long, slender bristle and 2 or 3 slender 

 hairs. Anterior sternopleuron with a tuft of fine pile ; 

 pteropleuron apilose ; the posthypopleuron has, in addi- 

 tion to pubescence, 4 or 5 long, slender hairs in a ver- 

 tical row. Metapleuron with a narrow, vertical band 

 of long, slender bristles and bristly hairs. Lateral 

 slopes of the metanotum with a large patch of short, 

 rather stout bristles; posterior half of the lateral meta- 

 sternum with numerous, long, stiff hairs on all except 

 the basal third. Postmetacoxal area with a chitinized 

 arch, nearly as long as the coxa, that bears on each side 

 a tuft of 8 or 10 fine, stiff hairs. Tegula pubescent 

 only. 



Legs : The hind femur is very little longer than the 

 middle pair, moderately swollen, narrowed from the 



