McLachlan, who described the 4-filamented gills of the larva of Rh. inter- 

 media McL. (MaLachlan, 1874-1880:78; Dohler, 1950:273-274).* Each 

 filament is divided by a deep constriction into two parts, the basal part 



234 shorter than the distal part, which is tapering at the end; the two upper 

 filaments sometimes have a second constriction in the distal third, so that 

 the filament appears 3 -segmented. The filaments become gradually shorter 

 and thinner on the abdominal segments, especially on segments 7 and 8. 



The dorsal sclerite of abdominal segment 9 is brown, without dots; the 

 black anterior margin is continuous, broader in the middle of each half, 

 narrower in the middle; the setae at the anterior margin are small and light, 

 situated near the margin; the posterior margin is marked only in form of 

 black dashlike parts at the base of the medioanal setae, which are black and 

 long; the anterior -angle setae are similar; the intermediate and lateral 

 setae are small and light; the former is situated near the outer margin of 

 the dash; the latter is situated slightly away from this dash. The latero- 

 ventral seta is thick and dark, situated on a sclerotized dot on the sides of 

 the segment. 



Dorsolateral sclerite "b" of anal legs (Figure 229) chestnut brown, with 

 large light dots which are more numerous in the basal part; the basal 

 and median margin of the sclerite is black, broader in the distal part; the 

 sword-shaped process is long and large; distodorsal tubercle high; baso- 

 ventral hook reddish brown; plate at the base of the hook golden brown, with 

 a light, short ventral seta; a short thick seta in the mediodistal corner of 

 the basal part of the sclerite; unlike in Rh. septentrionis, this seta is 

 less than half as long as the lateral seta of the distal part, which is also 

 black and thick but much longer; the second (mediobasal) seta of the distal 

 part is small, thin and dark. Sclerite "c" large, dark brown; lateral 

 sclerite with a black ventral margin; seta short and black. 



Basal part of the claw longer than apical part (Figure 229); it bears two 

 small blunt ventral spinules; setae 1, 3 and 5 long, strong and black; setae 6 



235 and 4 shorter and lighter; seta 2 short and thin; setae 7 and 8 transparent; 

 seta 8 situated on a tubercle. 



Mode of life and habitats. Mountain brooks and rivulets, with 

 cool water and stony bottom. 



Distribution. Greater and Lesser Caucasus. 



2. Rhyacophila bacurianica Lepneva (Rhy ac ophi la sp. 



"larva bacurianica" Lepneva) 



Lepneva, 1946:330-331, Figures 6-7; 1957:13; 1961:655-658. 



Full-grown larva. Length 17.0— 22.5 mm. Head large, broad, shorter 

 and broader than in Rh. forcipulata; head only slightly longer than broad 

 (Figure 230); anterior part of frontoclypeus shorter than posterior part, 

 completely dark or with a broad dark median stripe; 3 pairs of widely 

 separated dots at the anterior margin; a wide, dark, rhomboidal spot with a 

 curved row of 5—7 light dots in the posterior part; the lateral dots are 

 transverse and narrow. 



* McLachlan accepted Eaton's view and tentatively considered the larva with 4 filaments in the gills as 

 that of Rh. glareosa McL.; thislarvais named as such in the keys of Ulmer (1909:219) and Lestage 

 (1921:415); Dohler (1950) proved that this is the larva of Rh. intermedia McL. (cf. Lepneva, 1961: 

 652-653). 



246 



