light spots at the base of setae 15 and 16; ventral side with dark stripes with 

 longitudinal rows of large dots (Figure 231). 



Chaetotaxy as in Rh. forcipulata, with minor differences . 



Pronotum completely dark, smoky brown except in the small anterior - 

 angle part and with large, distinct dark dots. Two of the 5—7 small 

 anterior-margin setae situated inside to the anterior -angle setae are dark 

 and larger than the others (Figure 232). 



Thoracic gills shorter than in Rh. forcipulata, with rounded apex; 

 they are pinkish like the first 3 filaments of the abdominal gills in fixed 

 specimens; distal part of filaments of abdominal gills shorter than in 

 Rh. forcipulata; they are blunt and narrower at the apex, without 

 236 secondary constriction; the first three branches directed upward; ventral 



branch shorter, thinner and lighter than the others (often almost transparent) 

 and inclined posteriorly. 



Dorsal sclerite of segment 9 yellow, without dots; the black anterior 

 margin narrow in the middle; it is broader laterally like the large anterior- 

 angle parts, the black dashes at the base of the medioanal setae small and 

 narrow. 



Anal legs slightly shorter than in Rh. forcipulata; dots of 

 sclerite "b" present only in the dorsal part. Claw as in Rh. forcipulata. 



Mode of life and habitats. Brooks and rivulets with cool water 

 and stony bottom, mainly in high mountains. 



Distribution. Greater and Lesser Caucasus. 



4. Group Mesorhyacophila Lepneva 

 Lepneva, 1963:66-67. 



Full-grown larva. Larvae smaller than in the preceding groups; length 

 15— 19 mm; body slightly flattened dorsoventrally. Submentum as in the 

 preceding groups, with concave anterior margin and convex posterior 

 margin. Pronotum with 2 dark, long anterior-angle setae, one primary and 

 one secondary; 2nd secondary seta small or short. Thoracic gills isolated, 

 sausage -shaped (as in Pararhyacophila), or absent; abdominal tracheal 

 gills absent. Dorsal sclerite of segment 9 broad anteriorly, with large 

 anterior- angle processes extending to the pleural and partly to the ventral 

 side. The sword-shaped process of sclerite "b" of the anal legs is either 

 as in Rhyacophila s. str. in form of a lateral process of sclerite "b, " 

 of slightly irregular form or is situated nearby, on a separate small 

 sclerite. The claw bears large ventral spinules in its distal part, little 

 marked spinules, or spinules are absent. 



Mode of life and habitats. Brooks and rivulets with stony 

 bottom. 



Distribution. USSR: Talass Alatau, Altai, Sayans, Amur Region. 

 Also Japan, Sunda Islands, North America. 



Key to Species 



1 (4). Sword-shaped process broader at the base, situated on the distal 

 margin of the lateral part of sclerite "b. " 



248 



