Number and arrangements of gills of pupa of 

 S. nigricornis 



Mandibles (Figure 590, B) resembling those of Limnophilinae, but with 

 slightly shorter basal part; median blade serrated, with small, basal 

 spinules; ventral of 2 lateral setae smaller than dorsal. Fore and mid- 

 tarsi with natatorial setae, fore tarsi 

 dorsally on segments 1—4 and ventrally 

 on segments 1—3; mid-tarsi dorsally and 

 ventrally on segments 1—4. 



Abdominal segment 1 with strongly 

 sclerotized tubercles, covered with 

 spinules at posterior margin; plates of 

 holding apparatus on segments 3—7 with 

 hooks as follows: 111:2; IV: 2-3; 

 V:2-3 + 15-17; VI:2-3; VII:2-3. 



Gills on segments 2—7, gills in dorsal 

 row fewer than in larva. 



Anal rods (Figure 590, C) yellow, 

 brown basally, thin, long, curved at end, 

 with minute spinules, without setae. 

 Genital appendages of male pupae very 

 short, with rounded apex; penis sheath 

 small. 



Case attached to a stone at anterior 

 end by numerous ligaments with widened 

 end; anterior opening with a membrane and covered with a small stone, 

 membrane with small, slitlike, radial holes between stone and ventral naargin 

 of case (Figure 591, B); posterior membrane with several holes near ventral 

 margin (Figure 591, C). 



Mode of life and habitats. Phytophagous, feeding on algae, living 

 on stones or on plants among stones; in brooks and rivulets with a current 

 of 40— 70 cm/ sec; avoids rapid currents. Pupa emerges from case by 

 gnawing through anterior membrane and removing small stone; empty case 

 remains attached to stone for a long time. 



Distribution. Not recorded in the USSR, but possibly occurs at 

 western border. In addition, Europe. 



Segment 



Dorsal 



Ventral 



2 



2-3 



2 



3 



1-2 

 4 



3 

 4 



4 



2 



2 



4 



5 





2 



4 



6 





2-3 



4 



7 





1-2 



3. Genus Lithax McLachlan 



'47 



Full-grown larva. Length 8—12 mm. Body slightly tapering posteriorly. 

 Coloration mainly dark; dorsal side of head black or brownish black in 

 middle; posterior part of frontoclypeus much smaller than anterior part, 

 AS in Silo. 



Pronotum largely blackish. Mesonotum with 3 pairs of sclerites, 

 metanotum with 4 pairs. Case made of sand grains, slightly curved, 

 sometimes almost straight, slightly narrower posteriorly, flattened ventrally, 

 with large sand grains laterally, as in A pat a ni a. 



Mode of life and habitats. Rapid mountain brooks and rivulets. 



Distribution. The European USSR, including the Caucasus. In 

 addition, Europe. 



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