Case of young and full-grown lai-va tetrahedral, made of narrow, trans- 

 versely arranged pieces of detritus (Figure 635, B). 



Mode of life and habitats. Large, rapid, mountain rivers 

 (Terek, Teberda). 



Distribution. USSR: Northern and Central Caucasus. 



2. Genus Oligoplectrodes Mai-tynov 



Pull-grown larva. Length 12 — 14 mm. Head dark, with indistinct pattern 

 or with a pattern of light dots; seta 17 moderately long, thick, strong, dark 

 brown (Figure 63 6, A). Ti-ansverse ridge of pronotum less developed than 

 in Brachycentrus. Anterior surface seta of mid- and hind femora 

 moderately long, thick, strong, dark brown, in form of a large pointed spine; 

 prinnary distoventral seta of mid- and hind femora also unusual, in form 

 of a large, thick, blunt spine. 



Case tetrahedral, slightly narrower postei-iorly, made of detritus, 

 sometimes of secretion, without edges, dark, with round cross section. 



Mode of life and habitats. Mountain brooks and rivulets. 



Distribution. USSR: Northern Kazakhstan, Siberia, Altai, Sayans, 

 Kamchatka, Sakhalin. In addition, Mongolia. 



1. Oligoplectrodes potanini Martynov 

 Lepneva, 1949:184-186. 



Full-grown larva. Length 12— 14 mm. Head slightly oblong, mainly 

 reddish brown or bi-own, sometimes dark bi-own, with indistinct punctation; 

 periocvilai- spot brownish yellow (Figure 63 6, B); frontoclypeus with 2 pairs 

 of dots anteriorly, a ti'ansverse row of 4 — 6 dots posteriorly, including 

 2 large, median, and small, lateral dots; posterior corner of frontoclypeus 

 light brown, yellowish in light specimens. Four large, transverse dots 

 lateral to posterior part of frontal sutures; similar dots lateral to 

 2 posterior dots and near coronal sutui-e; ventral surface of head chestnut 

 brown in middle, light brown near occipital foramen, with large, light, and 

 brownish dots; some specimens with a distinct whitish yellow area at 

 posterior margin of gular suture. Gula wide, irregularly trapezoidal, with 

 slightly convex sides; posterior corner narrower, straight, or with a 

 shallow indentation; boundary with pregula with a nai-i'ow, reddish sti-ipe 

 (Figure 636, C). 



Anterior-margin setae reddish brown, short, very thick, latei-al seta 

 moderately long, lighter, and thinner; anterior frontal seta also lai-ge, 

 intei-mediate frontal seta smallei', situated at curvature of frontal sutures, 

 posterior frontal seta large, light; seta 7 situated lateral to antenna, light 

 brown, moderately long; seta 9 situated before eye, reddish brown, similar 

 to anterior- margin setae; seta 11 small, situated behind 9 near eye; 

 seta 14 large, moderately long, dark reddish bi-own, situated behind eye; 

 seta 12 situated laterally, light, moderately long; seta 13 short, situated 

 between 12 and 14 and slightly posteriorly; setae 15 and 16 situated on a 

 light spot, both reddish brown, 15 moderately long, longer and thinner than 14, 



478 



