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UNITED STATES NATIONAL MUSEUM BULLETIN 22 4 



short, stout, marginal bristles. The abdomen is cylin- 

 droid or slightly tapered, the posterior corners and an- 

 terior margins of the segments generally pollinose. 

 The tibial bristles are strong and femoral bristles are 

 weak. Length 5 to 12 mm. 



Head, lateral aspect : The head of medium length, the 

 face moderately prominent, strongly rounded and gib- 

 bous and rising from immediately beneath the antenna. 

 The occiput is everywhere short but slightly more 

 prominent below. The eyes are posteroventrally reces- 

 sive beginning at the middle of the head. Occipital 

 pile dense, long and fine below, with weak bristles be- 

 ginning on the upper fourth, which are arranged in a 

 broad, irregular patch behind the upper eye, containing 

 as many as 4 rows; there may be a single, deep, post- 

 vertical bristle. Proboscis small, short, cylindrical, a 

 little pointed at apex, not extending beyond the face. 

 Palpus generally long and slender, with two segments, 

 the first short and excavated, the second segment with 

 scattered bristly hairs below and laterally. Antenna 

 attached at the middle of the head, slender, nearly as 

 long as the head, the first two segments subequal and 

 a little swollen. The third segment at the base is not as 

 wide as the second segment ; it is there distinctly nar- 

 rowed to be again expanded or dilated broadly over the 

 outer third, and narrow at the apex. Two microseg- 

 ments are present, the first short, the second long, at- 

 tenuate, bent down and with a spine at the tip. Second 

 segment ventrally with 1 long, conspicuous, stout bristle 

 and sometimes 2 more slender ones. 



Head, anterior aspect: The head is wide, flattened, 

 the face wide and approximately two-fifths of the head 

 width. Lower face and front each slightly wider than 

 the upper face. Face coarsely pubescent with a few 

 scattered, fine, long hairs and more abundant, very 

 slender bristles beginning near the antenna and form- 

 ing a widening triangular patch below. Oral margin 

 without more strongly differentiated bristles. First 

 antennal segment with 2 or 3 stout bristles or with fine 

 pile only. Subepistomal area only moderate in size 

 and distinctly horizontal. Front nearly flat, pollinose 

 or pubescent and with numerous delicate hairs lat- 

 erally. Vertex moderately excavated, the ocellarium 

 exceptionally broad, rather low, the anterior ocellus 

 vertical and bearing 2 or 3 pairs of bristles between the 

 ocelli, a like number behind, and additional fine, long 

 pile. Anterior eye facets moderately enlarged. 



Thorax : The thorax is pollinose with rather scanty, 

 fine bristly pile. There is a double acrostical row, a 

 differentiated row of dorsoeentral bristles, sometimes 

 short, more often long and slender and becoming still 

 longer posteriorly. Humerus with fine, abundant pile. 

 The lateral complement of bristles is as follows: 2 to 

 3 notopleural, 2 strong and sometimes 2 weak supra- 

 alar, 2 postalar, and 2 to 6 pairs of scutellar bristles. 

 Scutellar disc rather flat, pubescent, apilose, or more 

 rarely with 2 or 3 slender bristles on each side near the 

 base. Propleuron and cervical sclerites with dense, 

 long, fine pile. Presternum dissociated. Remainder 

 of pleuron apilose; metapleuron with 6 to 15 long, 



slender bristles. Lateral and ventral metastemum 

 with fine pile; postmetacoxal area membranous. 



Legs: The femora are stout and a little swollen, 

 especially through the middle; their pile varies from 

 very short and Hat appressed to species where it is 

 so arranged only dorsally and the anterior and poste- 

 rior margins have a considerable amount of longer, 

 shaggy, subappressed pile. Femora with few bristles. 

 Hind femur laterally and dorsolaterally near the apex 

 with 3 to 5 bristles, and with 1 dorsomedial subapical 

 bristle. Middle femur with 1 long, dorsolateral bristle 

 at the outer fourth and generally 2 others near the 

 apex. Anterior femur with a dorsal row of 5 to 8 

 bristles and a small transverse cluster of bristles ante- 

 riorly at the apex. All femora usually with a vary- 

 ing number of quite long, bristly hairs or slender 

 bristles ventrally. Tibial bristles numerous and 

 prominent. Hind tibia with 5 ventromedial bristles 

 basally, 5 dorsomedial, 3 long, stout, lateral bristles, 

 and 5 or 6 similar ventrolateral bristles. Middle tibia 

 with the anterodorsal and posteroventral bristles exag- 

 gerated ; 8 bristles in the former row and 6 in the lat- 

 ter row. There are 6 posterodorsal and 3 long, ventral 

 bristles. Anterior tibia rather similar and in the males 

 with the dorsal bristles on the discal half multiplied 

 and long, slender, and conspicuous. This continues on 

 to the male fore tarsus where the dorsal bristles are 

 longer and conspicuous in some species. Protibial 

 apex without spine. Claws, sharp; empodium swollen 

 at the base; pulvilli well developed. 



Wings: The wings are slender; marginal cell is 

 widely open, fork of the third vein lies beyond the pos- 

 terior crossvein. Anterior crossvein enters the wing 

 at or just beyond the middle of the discal cell, or rarely 

 just before the middle. All the posterior cells widely 

 open. Anal cell open or narrowly closed. Alula 

 short ; ambient vein complete. 



Abdomen : The abdomen is comparatively short and 

 robust, slightly tapered ; at the base nearly as wide as 

 the mesonotum, quite bare in appearance, with short, 

 scanty, appressed, setate pile and a few fine, more erect 

 hairs along the sides of the first two tergites. Abdomen 

 mostly shining or dull black with the posterior corners 

 and the anterior margins pale pollinose. Males with 

 seven tergites, the seventh sometimes only half as long 

 as the sixth. The eighth may be present as a short lip 

 or concealed beneath the seventh. Females with eight 

 tergites, the last bemg short. Male terminalia not very 

 large, the epandrium broad, with a short, apical, tri- 

 angular cleft, which is filled by a membrane. Gonopod 

 short, triangular, bluntly pointed at the apex. Hy- 

 pandrium broad at the base, elongate and narrowed 

 apically, the genital cavity exposed. Females with 4 or 

 5 pairs of short, stout, truncate spines on the 

 acanthophorites. 



Distribution: Nearctic: Nannocyrtopogon antenna- 

 tus Wilcox and Martin (1957) ; anstatus James (1942) ; 

 arnaudi Wilcox and Martin (1957); atripes Wilcox 

 and Martin (1936) ; bmneri Wilcox and Martin 

 (1957) ; cerussatus Osten Sacken (1877) ; crumbi Wil- 



