350 



IV. Family LEPIDOSTOMATIDAE Ulmer 



Full-grown larva. Length 7—11 mm. Head wide (as long as wide or 

 slightly longer), brown or dark brown, with large, light, more or less oblong 

 dots; eyes situated in middle of head; antennae at anterior margin of 

 periocular spot; :frontoclypeus, as in Limnophilidae, with equally large 

 anterior and posterior part; gula slightly oblong, triangular oval. Mandibles 

 black, short, chisellike; teeth distinct, situated at apex; brush situated near 

 dorsal margin on both mandibles. Pi-onotum wide, with slightly projecting 

 anterior margin; anterior angles rounded; posterior margin broad. Meso- 

 notum lighter posteriorly, weakly sclerotized in some species; dots some- 

 what oblong, light, large. Mesonotum, as in Limnophilinae, with or without 

 3 small sclerites. Forelegs much shorter and more massive than the thin, 

 long, mid- and hind legs. Gills single, in dorsal and ventral rows. Tergite 

 of abdominal segment 9 weakly sclerotized or absent. Claw of anal legs with 

 1 or 2 dorsal denticles. 



Case made of sand grains, conical, straight, or slightly curved; those 

 made of detritus are tetrahedral, with small, regularly arranged particles. 



Mode of life and habitats. Running water, including spring-fed 

 brooks; mountain brooks, and rivulets, rarely near banks of large rivers; 

 open littoral of lakes. 



Distribution. Throughout the USSR. In addition, Europe, Africa, 

 Asia, North and Central America, Madagascar. 



Key to Genera 



1 (4). Mesonotum well differentiated, sclerotized posteriorly, ending 



before posterior margin of segment in some species. Metanotum, as 

 in Limnophilinae, with 3 pairs of small tergites. 



2 (3). Head and pronotum brown or light brown, light dots of head mainly 



oblong; mesonotum lighter than pronotum; setae brown or light 

 brown; case made of detritus, tetrahedral or conical; case made of 

 sand grains, straight; widely distributed in European and Asiatic 

 parts of the USSR 1. Lepidostoma Ramib. (p. 438) 



3 (2). Head and pronotum reddish brown, dots mainly round; mesonotum 



much lighter than pronotum; setae mainly dark brown or black; 

 case made of sand grains; Caucasus, Asiatic part of the USSR .... 

 2. Dinarthrum McL. (p. 445) 



4 (1). Mesonotum indistinctly sclerotized posteriorly, merging gradually 



with membranous part; small tergites of metanotum indistinct; 

 western part of the European USSR. 



5 (6). Head dark, chestnut brown; light dots mainly in form of streaks, 



round dots less numerous; case conical, made of sand grains, 

 slightly curved 4. Lasiocephala Costa(p. 460) 



6 (5). Head lighter dorsally, dark reddish brown, with oblong dots ventrally; 



case tetrahedral, made of large pieces of detritus 



3. Crunoecia McL. (p. 454) 



437 



