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UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



middle toward the base, though only slightly. It is 

 comparatively thick throughout ; hind tibia also ro- 

 bust, except quite close to the base, where it is a little 

 narrowed. The hind tibia is four-fifths as long as the 

 femur. Dorsal surface of the hind femur with short, 

 bristly, appressed setae a little more abundant medially. 

 Ventral surface on the medial half with a dense brush 

 of long, fine, pale, erect pile and the base only with 

 2 or 3 fine, long hairs of twice the length of this brush. 

 Hind tibia with a similar brush of pile and 8 longer, 

 slender, bristly hairs with no setae at the apex. In 

 these flies the bristles are all exceptionally weak and 

 for the most part little more than bristly hairs. On 

 the middle tibia only do they stand out conspicuously 

 as an anterodorsal and anteroventral fringe of excep- 

 tionally long, basally stout, strongly attenuate fringe. 

 The following complement of bristles is present: On 

 the hind femur at the outer fourth are 3 bristly hairs 

 dorsomedially and 3 dorsolaterally in a longitudinal 

 row; also ventrolaterally 5 or 6 slender, bristly hairs 

 and 1 quite long, bristly hair in the middle, another 

 ventromedially before the middle. Hind tibia with 

 4 or 5 posterodorsal, bristly hairs; a like number 

 dorsolaterally, of which one at the outer third is dis- 

 distinctly longer and stouter. 



Middle femur quite slender with a bristle only an- 

 teriorly at the outer fourth. Ventral surface with a 

 rather regular, double row of long, yellow, bristly 

 hairs, longer toward the base. Middle tibia with 4 

 quite long, oblique, basally stout, anterodorsal, black 

 bristles and 7 or 8 shorter, posterodorsal, bristly hairs; 

 also 9 or 10 similar, posteroventral bristly hairs and 

 with 4 exceptionally long, basally thickened, black, 

 oblique, anteroventral bristles. Anterior femur similar 

 to the middle pair but without bristles, with compara- 

 tively long, black, bristly pile posteriorly. There is 

 similar pile dorsally, posterodorsally, and laterally on 

 the anterior tibia. This tibia also has 3 or 4 longer, 

 posteroventral, slender bristles or bristly hairs. The 

 bristles of the tarsal segments comparatively long on 

 the first two segments of the anterior tarsus; claws 

 small, sharp; pul villi long; the empodium long and a 

 little flattened basally. 



Wings: The wings are narrow at the base, due to 

 the long, narrow axillary lobe. Marginal cell closed 

 with a quite short stalk but comparatively broad 

 apically. First, second, and third posterior cells widely 

 open; fourth closed with a moderately long stalk. The 

 anal cell closed with a long stalk; second basal cell 

 ends in two veins, the anterior crossvein enters the 

 discal cell at the distal third ; the end vein of the discal 

 cell and the fourth posterior cell are quite in align- 

 ment although they do not form quite a straight line. 

 Alula less wide than the costal cell; the ambient vein 

 complete. 



Abdomen : The abdomen is short and robust with a 

 tendency to be rather thinned or flattened. In the 

 female the tergites laterally are strongly offset from 

 one another at their basal corners. In the male they 

 appear to be quite smooth but this appears possibly 



due to the fact that these edges are rather strongly 

 curled inward. Pile of abdomen dense, bristly setate 

 and subappressed but with longer, bristly pile on the 

 sides of the first three tergites. Sides of the first 

 tergite near the middle with 2 or 3 slender bristles. 

 Pile and bristles of male black; of female, except the 

 anterior corners, brassy yellow on the sides of the 

 first three tergites and dorsally on the first five tergites, 

 where it is flat appressed and rather thick and matted. 

 Basal margins of the tergites strongly sloping, leaving 

 a deep, shallow crease between each segment. Males 

 with seven tergites, the seventh from a fourth to a 

 third as long as the sixth ; females with seven tergites, 

 the seventh of the same length as the male in propor- 

 tion to the sixth. The terminal segments are not 

 cupped so that the short terminal i a are exposed in both 

 sexes from a lateral aspect. 



Distribution : Neotropical : Lamprozona atrata 

 Philippi (1865) ; auricincta Loew (1851) ; castaneipes 

 Bigot (1878) ; chilensis Brethes [ = cyanescens Bigot 

 (1878) notBondani]. 



Genus Loivinella Hermann 



Figures 219, 656, 1351, 1360, 2173 



Lowinella Hermann, Nova Acta Acad. Caes. Leop.-Carol., vol. 

 96, p. 104, 1912. Type of genus: Atomosia virescens Loew, 

 1871, by original designation. 



Quite small, robust flies; the abdomen and mesono- 

 tum punctate and separated from the other genera of 

 the Atomosini by the stout, comparatively large micro- 

 segment with apical, bristly spine which is attached to 

 the third antennal segment. Length 6.5 to 10 mm. 



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

 tuberant on the upper third but moderately protuberant 

 and gently convex on the lower third, leaving the inter- 

 vening area barely concave. The eye is comparatively 

 long, quite convex anteriorly, plane across the middle 

 posteriorly for at least half of its total height, but rather 

 strongly recessed below and only slightly above. The 

 occiput is quite short but developed throughout the 

 height of the head. The pile of the occiput is only 

 moderately abundant and long and fine on the ventral 

 fourth of the head, but is short and scanty through the 

 middle and absent dorsally. Beginning in the middle 

 are 7 or 8 pairs of rather short, but exceptionally stout, 

 spinous bristles ; 2 or 3 of these bristles are located on 

 each side behind the vertex. Proboscis unusually short, 

 not quite as long as the face, robust and stout, cylindri- 

 cal and bluntly rounded. The apex bears numerous, 

 short, stiff hairs above and below, the base ventrally has 

 only 2 or 3 fine, long hairs. The proboscis is directed 

 horizontally forward. The antenna is attached at the 

 upper fourth of the head and is elongate and slender ; 

 the first segment is slightly longer than the second. The 

 third segment is not quite l 1 ^ times as long as the first 

 two segments combined, of uniform width and almost 

 cylindrical ; it bears a comparatively long, robust micro- 

 segment which dorsally near its base is notched or ex- 



