292 seta short and dark; lateral plate of this part larger, yellowish and with a 



narrow, reddish brown, oblique, basal stripe. Median membranous surface of 

 segment dark in a large part because of the numerous chetoids. 



Claw (Figures 332, 333, 334) very long and narrow, weakly curved; 

 transverse membranous stripe situated in about the middle of the claw; the 

 basal border narrow; basodorsal process low; claw covered with dense 

 chetoids as the other sclerites of the larva; distal part with 5 strong, blunt 

 and short reddish brown spinules ventrally. Dorsal seta 1 situated at the 

 base of the claw, light, thick, very long, directed posteriorly, recumbent on 

 the claw; dorsal seta 2 similar but shorter, situated slightly laterally, near 

 the transverse membranous stripe; setae 4 and 5 are situated on the outer 

 side and medially; they are similar to seta 1 and extend almost to the apex 

 of the claw; long ventral seta 8 curved, basal seta 7 shorter; the short light 

 setae 6 and 3 are situated one behind the other in the distal part on the 

 outside; seta 3 situated close to distal margin of claw. When the claw is 

 bent, it touches the ventral hook of the leg, forming a loop with which the 

 larva grasps stalks of moss or other material, holding itself or hanging in 

 the current; the second hook and the beak-shaped process of the basoventral 

 plate are additional tools of support, instead of the sword-shaped process. 



Mode of life and habitats. High -mountain spring brooks, 

 among stones overgrown with moss. 



Distribution. USSR: Lesser Caucasus, high-mountains of the 

 Trialet Range. Not recorded outside the USSR. 



Subfamily HYDROBIOSINAE Ulmer 



Full-grown larva. Size of larvae varying from 6.5—10.0 mm to 22—28 and 

 even 30 mm;* live specimens are green or opaline white. Head, especially 

 anteriorly, dorsoventrally flattened; frontoclypeus without deep lateral 

 notches; gula small. Prothorax narrower posteriorly; pronotum wide; 

 legs situated near the anterior margin of the segment. Meso- and 

 metathorax much larger than the prothorax. Forelegs highly specialized, 

 with an oblong rodlike coxa and very short, sometimes fused tibia and tarsus; 

 with rare exceptions, the femur has a large distoventral process which forms 

 a chela with tibia and tarsus (resembling the chela of Crustacea), or (as in 

 species of Apsilochorema) femur, tibia, tarsus and claw have a different 

 structure. Midlegs and hind legs long, thin and normal. Abdomen of small 

 species almost cylindrical; it is slightly flattened ventrally in large 

 species. Tracheal gills absent. Larvae are without case. One genus in 

 the USSR. 



Mode of life and habitats. Various types of flowing water. 



Distribution. USSR: Middle Asia, Far East. In addition: southern 

 Asia, Australia, New Zealand, North and South America. 



Only small species occur in the USSR. 



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