straight sides, rounded anterior margin and distinct anterior angles; 

 2 anterior -margin setae rudimentary; 2 small median setae and 2 long 

 lateral setae posteriorly. Mandibles with a long distal part which is 

 serrated on the inner side; outer basal setae of different length. 



The oblong presegmental plates of the holding apparatus of segments 3—7 

 bear 4—8 spinules, the postsegmental plates of segments 3—5 with 

 4—13 spinules. Posterior margin of segment 8 of the male pupa concave, 

 dor sally penis visible ventrally in the middle; there are lateral lobes; end 

 of the body with two median groups of spinules on the ventral side; end of 

 female pupa blunt, with two lobes. Case 3—4 mm long; anterior angles with 

 one disk or rarely two small disks on each ligament; posterior disks 

 sometimes situated close together; they are sometimes replaced by one disk 

 with two stalks; case yellowish green or grayish. 



Mode of life and habitats. Rivulets and in plant thickets. 



Distribution. USSR: northwest of the European part. In addition, 

 Europe. 



3. Oxyethira distinctella McLachlan 



Lepneva, 1928:37-39, Figures 3 and 4. 



Full-grown larva. Length 2.5— 3.0 mm. Head light yellow; a narrow 

 brown border near the occpital foramen; dark spots at the base of the 

 middle frontal setae (Figure 448); frontoclypeus (Figure 449) dark in the 

 middle, with indistinct spots posteriorly. Antennal seta situated subapically 

 on the sensilla, at jz of its length (Figure 450). Pronotum light yellow 

 anteriorly, brown or dark brown laterally and posteriorly; its posterior 

 margin with a dark brown border; mesonotum light yellow in its greater 

 part; its posterior margin with a narrow brown stripe; metanotum brown, 

 dark brown posteriorly. Prosternum (Figure 451 ) and mesothoracic 

 sternites brown; median sternite of metathorax indistinct, light yellow, 

 irregularly triangular. Distoventral process of tibia of forelegs with a 

 row of short, thin, dark spinules which form a brush on the outer side 

 (Figure 452). 



Abdomen slightly curved. 



Case (Figure 453) with a short neck; anterior opening broad; sides of 

 the case parallel posteriorly. 



Pupa. Length 2.9— 3.0 mm. The broad anterior end of the case is 

 slightly convex, almost straight; each angle with one disk. 



Mode of life and habitats. Plant thickets in stagnant and 

 running water with a slow current; they prefer calm parts of thickets of 

 water lilies and broad-leaved Potamogeton in lakes; they avoid the 

 open littoral with reeds and Scirpus; pupae are found in June, July and 

 August. They have been found in lakes Segozero, Bygozero, Sandal and the 

 lakes of the Vygoonezhskii watershed in Karelia. 



Distribution. Northwest of the European USSR. In addition, 

 Europe. 



384 



