covered with shrubs in forests, floodlands and near springs accumulate 

 leaves and needles of trees, roots and twigs, and form typical biotopes fed 

 by spring water. These biotopes are well ventilated and consist of layers 

 of leaves, twigs and coarse detritus; they are inhabited by a characteristic 

 fauna which is isoecological with the inhabitants of the fauna hygropterica. 



In the northwest of the European USSR, springs of various types are 

 numerous on the Silurian plateau; underground water emerges on their 

 bottoms, often forming large limnocrens, numerous rheocrens, which give 

 origin to brooks and marshy spring ponds. In rheocrens Rhyacophila 

 s e pt e nt r i on i s usually occurs at a temperature of 5— 10°; however, this 

 species is also found further downstream, in brooks with a summer 

 temperature of 11 — 16°. It occurs there together with Rhyacophila 

 nub il a, which does not occur at a lower temperature (Lepneva, 1930; 

 Nielsen, 1942:263). Larvae of Rhy a c op h i 1 a ob 1 it e r at a were found in 

 springs in some localities (Latvia, Yaroslav Region). Larvae of 

 Wormaldia subnigra, Plectrocnemia conspersa, Apatania 

 zonella, Potamophylax stellatus, in some places Parachiona 

 picicornis and Chaetopteryx villosa occur on the stony 

 bottom of rheocrens. The fauna of limnocrens is poorer, e. g., the species 

 Apatania zonella, A. wallengreni, Silo pallipes, Chaetop- 

 teryx sp., Potamophylax stellatus.* In the humid vegetation of 

 floods and in the littoral stripe of springs the small larvae of Berea 

 pullata, larvae of Crunoecia irrorata (with their tetrahedral 

 detritus-covered cases) and larvae of Potamophylax nigricornis 

 (the cases of which consist of sand or partly of detritus) are found. 



In the rheocrens of the Caucasus, especially in Transcaucasia (spring 

 zone of the Tskhra-Tskharo massif and the upper reaches of the Bakurianka) 

 live a rich fauna of Rhyacophila, especially larvae of Rh. bacurianica 

 and Rh. forcipulata (the gills of which have four short, thick, segmented 

 filaments (Figure 228)), larvae of Rh. subovata, etc. Where the river 

 bed descends steeply, larvae of Philocrena trialetica may be found 

 under stones ranging among the moss; these larvae are a typical local 

 endemic element of the spring fauna of the Caucasus. The species 

 Agapetus sp., P 1 e c t r o en e m ia latissima, Apatania subtilis, 

 Ernodes saltans, Dinarthrum tchaldyrense also belong to the 

 spring forms of the Caucasus (Zhadin, 1940:685; Lepneva, 1946:325-331; 

 1956:901-909; 1957:13; 1961:652-658; Martynov, 1926a:59). 



The larvae of Rhyacophila obscura, Glossosoma dentatum, 

 Agapetus sp., Dolophilodes sp., Hydropsyche sp., Apatania 

 copiosa, P s e u d o s t e n ophy 1 ax secretus, Limnophilus asia- 

 ticus, Dinarthrum pugnax live in springs on the Hissar Range and 

 other localities in Middle Asia; in higher localities one occasionally finds 

 Himalopsyche gigantea (= Rhyacophila gi ga nt e a) (Lepneva, 

 1945:70; 1951:155; Martynov, 1927b:477, 485). 



Sometimes large numbers of larvae of Ecclisomyia digitata 

 (= Praecosmoecus digit at us) may be found on stone slabs in 

 mountain springs in the Altai near Lake Teletskoe (Korbu Valley) in 

 shallow ponds with a water temperature of 6—7° (Lepneva, 1949:61; Schmid, 

 1955:59). 



* The name Potam ophylax Wall. (Schmid, 1955:175) does not correspond with the ecology of the 

 speciesP. stellatus, which, like other species of the genus, is restricted to small running water bodies; 

 this species thus belongs to an ecological group which differs from the fauna of rivers in the plains 

 (potamophiles, potamobionts). 



106 



