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large dark brown figure occupies the greater part of the posterior part of 

 the pronotum; this figure bears groups of dots which are not always 

 distinct. Two long setae, a primary and a secondary, in the light anterior- 

 angle notch; the seta between them small and indistinct; anterior margin 

 near the notch with 3 or 4 small setae, the anterior angle with 2 or 3; 

 surface setae as in Rh. septentrionis. 



Legs yellow and without dots; tarsi and claws brownish; dark spots near 

 the tibiofemoral articulation, on femur and tibia. Setae as in Rh. sep- 

 tentrionis. 



Dorsum of abdominal segments with a delicate light pattern consisting 

 of dashes on the anterior margin, two longitudinal stripes and transverse and 

 oblique dashes on the posterior margin which are distinct on the greenish 

 background in live specimens and on the violet background in freshly fixed 

 specimens. As in all species of Rhyacophila s. str., the tracheal gills 

 consist of a short, thick ventral branch with filaments near the apex, and of 

 a longer, thinner dorsal branch with filaments on its dorsal side; each gill 

 has 16—20 filaments. 



The dorsal sclerite of segment 9 has a broad serrated, black anterior 

 margin (Figure 212); narrow, sometimes interrupted black stripes are 

 present on the lobes near the posterior margin; the setae at the end of the 

 lobes (anterior angle and medioanal seta) are black; between them a small, 

 thin intermediate seta and a lateral seta; anterior -angle setae small and 

 hardly noticeable. Sclerites of anal legs brownish, with indistinct dots; 

 Basal and median margin broad and black (Figure 213); setae of claw 

 (except the light setae 7 and 8) black. 



Pupa. Length 12.0— 14.5 mm. Antennae of male pupa extending to 

 abdominal segments 7—8, those of the female pupa to abdominal segment 5; 

 blade of left mandible with 2 teeth, blade of right mandible with 3 teeth; 

 the blades are serrated, except the basal tooth. 



Wing sheaths extending to abdominal segments 4—5; natatorial setae 

 present on segments 1—4 of the mid-tarsi; they are sparse on the 1 st segment. 

 Claws of forelegs and midlegs thick and pointed; those of hind legs weaker 

 and less curved. Number of spinules of the holding apparatus as follows: 

 III : 0+ 25-30; IV : 20-35+ 35-45; V : 4-50+ 30-35; VI : 35-40; 

 VII : 30-35. 



Pupal case built of small stones or large sand grains, 20 mm long, 

 about 17 mm broad. Pupa with a wide, semitransparent cocoon which is 

 13—17 mm long and 3.0—3.5 mm broad. 



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

 water, on solid bottom, usually on stones, often on pieces of wood. 



Distribution. European USSR, mainly North and Northwest, 

 common in the Northern and Central Urals, rare in the Caucasus. Also: 

 Europe, Iran. 



5. Rhyacophila subnubila Marty no v, larva nova 



Full-grown larva. Smaller and of lighter color than Rh. nub i la; length 

 15— 17 mm; main coloration of sclerites whitish; pattern brown, sometimes 

 pale; dots indistinct. The species closely resembles Rh. nubila. The 



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