All 4 setae of tarsus of midlegs and hind legs thin, arranged strictly 

 symmetrically; dorsal setae longer than ventral setae; both pairs of setae 

 on forelegs shorter than on the other legs; difference in length small. 



Claws short and strong, their basal seta small, blunt and light. 



Dorsal sclerite of abdominal segment 9 (Figure 286) with small, dark 

 anterior -angle processes and rounded posterior processes; anterior -angle 

 and medioanal setae black and long, the latter widely separated; between 

 them, in the middle of the posterior margin, two large brownish dots which 

 are also present in Rh. sibirica; intermediate and lateral setae short 

 and thin. 



Anal legs (Figure 287) long as in all species of Hy po r hy a c o ph i 1 a. 

 Dorsolateral sclerite "b" brown, black at the base; trough-shaped grooves 

 dark; the sword-shaped process of Rhyacophila s. str. is replaced by 

 a small process; basoventral hook of the sclerite reddish brown, with a 

 black base, the sclerite near it small and yellow; seta on this sclerite 

 straight and light; lateral seta of the distal part of the dorsolateral sclerite 

 black and long, much longer than the claw; the seta of the distal part of 

 the sclerite long and black, similar to the lateral seta as in R h. sibirica; 

 posterior seta near the seta of the basal part dark but much shorter. 

 Unlike in 5th-stage larvae of Rhyacophila s. str., such a ratio is also 

 present in the lst-stage larvae of this group. Ventral sclerite of sclerite 

 "c" brownish and small, the seta on it yellow, similar to the ventral seta; 

 lateral sclerite "c" thin and yellow, irregularly rhomboidal. 



As in all species of Hy p o r hy a c o ph i la, the claws (Figure 287) are 

 long, their basal part almost straight, with a black, upward-directed, dorsal 

 process at the base; distal part uniformly curved; arrangement of the 

 setae as in Rh. sibirica; dorsal seta 1 longer than seta 2; seta 3 

 situated dorsally, in the distal part; the basal seta 5 longer than distal seta 6; 

 mediobasal seta 4 situated near the suture, thin and short; ventral setae 7 

 and 8 transparent and curved; seta 7 only slightly shorter than seta 8. 



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

 on stony bottom with a rapid or moderately rapid current; on the lower 

 surface of stones. 



Distribution. USSR: Amur Region and Maritime Territory. 



3. Rhyacophila lata Martynov 



Levanidova, 1962:193-194, Figures 4-5. 



Full-grown larva. Length 12—14 mm. Sclerotized areas chestnut brown; 

 the large setae of the same color and very thin at the end. Head oblong 

 (Figure 288), narrow, dark, 1.2 mm long and 0.75 mm broad; eyes small, 

 situated on a whitish yellow area; area near the occipital foramen light 

 brown. Frontoclypeus with an oblong posterior part; anterior part 

 narrower than posterior part, with two large pale dots laterally; posterior 

 part with a transverse row of similar dots. Lateral anterior-margin and 

 intermediate setae transparent, small, the former slightly thicker, situated 

 lateral to the frontal suture; median seta large and yellowish. Anterior 

 frontal seta recumbent; middle seta small, straight and strong, situated near 

 the curvature of the frontal sutures; posterior frontal setae chestnut brown, 



285 



