6 (s). Length 12— 14 mm; ventral side of femur with spinules only; gills 

 single; case tetrahedral, made of large, coarse pieces of detritus, 



rarely of secretion, blackish brown; the Asiatic USSR 



2. Oligoplectrodes Mart. (p. 478) 



Pupa 



1 (4). Case made of sand grains, conical, narrower posteriorly, smooth. 



2 (3). Length 6— 10 mm; gills absent or present only on dorsal side, small, 



single 4. Micrasema McL. (p. 492) 



3 (2). Length 10—12 mm; gills with 2—3 filaments, in dorsal, pleural 



(segment 2), and ventral rows .... 3. Oligoplectrum McL. (p. 485) 



4 (1). Case tetrahedral, made of detritus, rarely of secretion. 



5 (6). Gills forming tufts; case 11— 14 mm long, made of regularly arranged, 



straight, thin pieces of detritus; case yellowish or brown when made 



of secretion; the European USSR, Siberia 



1. Brachycentrus Curt. (p. 463) 



6 (5). Gills single; case 13— 16 mm long, made of detritus, tetrahedral, 



detritus particles coarse, not always smooth, or made of secretion, 



blackish brown; the Asiatic USSR 



2. Oligoplectrodes Mart. (p. 478) 



1. Genus Brachycentrus Curtis 



Full-grown larva. Length 8—12 mm. Dorsal side of head light yellow, 

 with distinct, dark pattern, or entirely dark, chestnut brown. Mesonotum 

 sclerotized, with 2 sclerites on each side; metanotum membranous, with a 

 transverse, curved row of 4 small, dark sclerites. Mid- and hind tibiae 

 with large distoventral process; claw thin, very long. Gills short, with 

 1—7 filaments. Case tetrahedral, made of transversely arranged, small 

 pieces of detritus, rarely of mineral particles, sometimes of secretion. 



Pupa. Length of male pupae, 8 mm, of female 10 mm. Antennae reaching 

 segments 6—8 or end of body. Number of spurs 2, 3, 3. Gills on 

 segments 2 — 6. Case as in larva, anterior and posterior membranous covers 

 with several small holes; case attached at anterior and posterior end. 



Mode of life and habitats. Running water of various types. 



Distribution. The European USSR, including the Caucasus; Middle 

 Asia, Siberia, the Amur region. In addition, Iran, Pakistan, China, Japan, 

 North America. 



Key to Species 

 Full-grown larva 



1 (4). Case made of detritus or secretion. 



2 (3). Head yellowish dor sally, with distinct, dark pattern in middle; 



widely distributed 1. B. subnubilus Curt. (p. 464) 



463 



