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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



PABT 1 



gradually but very slightly extended near the epistoma. 

 The occiput is prominent through all the middle por- 

 tions of the head, sloping gradually down to the eye 

 level, near the vertex and also below. The proboscis is 

 prominent, stout, bluntly pointed and cylindrical ; usu- 

 ally directed forward, it extends well beyond the face. 

 Palpus of one segment, moderate in size and clavate. 

 The antenna is attached near the upper fourth of the 

 head and is moderately elongate and slender ; the first 

 two segments are short and rather beadlike. The third 

 segment is usually elongate and attenuate, especially 

 at the apex and about twice as long as the first two; it 

 may be considerably shorter, and no longer than these. 

 The style is thick, distally dilated and varies from half 

 to twice the length of the third segment. It has a 

 small, short bristle at the apex. First two segments 

 with bristly pile ventrally at the apex. 



Head, anterior aspect : The face is generally narrow 

 at the antenna, usually varying from a twentieth to a 

 tenth the head width, but sometimes almost eliminated 

 by the encroachment of the eyes on the upper half of 

 the face, producing a near holoptic condition. The face 

 is always strongly divergent below, the subepistomal 

 area small, oblique, concave and pubescent. Face 

 pubescent, apilose, with 1 or 2 close-set rows of gen- 

 erally strong or sometimes quite weak bristles immedi- 

 ately above the epistomal margin. They may consist 

 of as few as 2 pairs. Front small, pubescent, divergent, 

 the vertex moderately excavated with nearly vertical 

 sides or sometimes scarcely at all. Generally there is 

 a recess posteriorly, the ocellarium moderately large 

 and set anteriorly forward and pubescent only. 



Thorax: The mesonotum is high, abrupt anteriorly 

 and often overhanging the pronotum with the medial 

 portion more protuberant. The whole surface may be 

 pubescent, pollinose or largely bare. The pile is qiute 

 scanty ; weak, short, acrostical, bristly hairs are present 

 and short, fine, dorsocentral elements present poste- 

 riorly. The posterior suture is quite far to the rear 

 and often behind the hind coxa. The lateral comple- 

 ment of bristles, generally stout, is 1 notopleural and 

 1 supraalar bristle. Scutellum thin, flattened and 

 pollinose, sometimes with a few, minute setae on the 

 rim. Metanotal callosity pollinose only. Pleuron 

 pollinose or pubescent, with a little, fine pile on the 

 anterodorsal mesopleuron and anterior sternopleuron, 

 and rarely a few hairs on the propleuron. The prono- 

 tum, pteropleuron, and hypopleuron are all without 

 pile, and usually the metapleuron as well. The meta- 

 pleuron is reduced and compressed by the great devel- 

 opment of the metasternum, which forms a long, 

 complete, chitinized arch in many species and in any 

 case is elongate. Presternum dissociated in some spe- 

 cies, in others undissociated. 



Legs: All the femora and the tibiae elongate, espe- 

 cially the hind pair, which are often very long; usually 

 all of the femora are more or less dilated or swollen 

 distally but this is accentuated on the hind pair. Pile 

 of legs dense, fine and subappressed on the dorsal and 

 lateral and posterior surfaces. Often the pile forms 



dense brushes of variable distribution of nearly erect, 

 fine pile on the ventral surface of the hind femur, the 

 other 4 femora nearly bare ventrally, and such brushes 

 may be absent on the hind femur. Bristles are almost 

 absent, being nearly restricted to the apices of the 

 femora and tibiae, more rarely there are a few bristles, 

 1 or 2 in number on the dorsal surface of the tibiae; in 

 some species there may be on the hind tibia 2 anterior 

 bristles, 3 or 4 ventrolateral bristles, on the middle tibia 

 4 posteroventral bristles, the anterior tibia being similar. 

 Apical bristles are strongly developed, the hind tibia 

 having 5 large bristles and 1 or 2 minute bristles. An- 

 terior tibia never with spine. Basitarsus as long as the 

 next 2 and sometimes the next 3 segments. Claws 

 stout, apposed, gently curved, sharp; the empodium 

 from one-third to two-thirds as long as the claws, or 

 absent in one subgenus ; pul villi always absent. 



Wings : The wings are slender, the marginal and all 

 posterior cells and the anal cell widely open. Alula 

 absent, ambient vein complete. The medial crossvein 

 forming the discal cell is generally rectangular; the 

 furcation of the fourth vein often lies at a considerable 

 distance from this crossvein. The posterior or third 

 branch of the medius and the anterior branch of the 

 cubitus or posterior intercalary vein are often fused for 

 a long distance. 



Abdomen : The abdomen is slender, elongate, reach- 

 ing well beyond the wings, cylindrical and pollinose 

 with fine, scanty, subappressed pile which tends to be 

 setate posteriorly. Only the first tergite has lateral 

 bristles. Male with eight tergites, the eighth reduced 

 in length, especially toward the middle. Females with 

 eight well developed tergites. Male terminalia gen- 

 erally moderate in size, never rotate, the superior for- 

 ceps short, more or less slender apically but in some 

 species elongate. The forceps sometimes bear long, 

 extraordinary prongs or processes. The dorsal proc- 

 tiger large and oblique. The gonopod and hypandrium 

 appear sometimes to form a more or less broad, convex, 

 fused, ventral, bulbous structure, or the hypandrium 

 may be narrow and elongate but distinct. Female ter- 

 minalia short and inconspicuous, mostly recessed be- 

 neath the eighth tergite. 



Leptogaster is the largest genus within the subfamily, 

 containing about 120 species. There are numerous 

 species in North America but few in Europe ; the genus 

 is especially well developed in southern Asia and the 

 South Pacific and members are often found on islands. 

 The adults frequent grassland and especially the herb- 

 age deep within forests. They hang by the forelegs 

 from tip of leaves when feeding or mating. Fossil 

 species are known as far back as the Oligocene. The 

 venation of Leptogaster is certainly highly generalized 

 and strongly resembles the venation of certain tipulids, 

 which are also slender, long-legged forest types. A 

 few species are only 6 or 7 mm. long and correspond- 

 ingly threadlike and delicate. 



Distribution: Nearctic: Leptogaster aegra Martin 

 (1957) ; altacola Martin (1957) ; arborcdla Martin 





