184 



185 



a moderately long and a short seta at median margin, both thick, black; 

 2—3 moderately long, thin, and 5—6 smaller setae on surface; ventral seta 

 thick, moderately long, black, or dark brown. Sclerite "c" yellowish brown, 

 with broad, black, lateral margin; basal seta short, thick, reddish brown. 



Claw mainly light brown, dark reddish brown apically, with a large, thick, 

 dorsal denticle, 4 minute, light spinules near base of denticle. Dorsal setae 

 brown; seta 1 situated subdorsally on median side of basal part, short, thick; 

 seta 2 moderately brown, thin, situated near lateral margin: seta 3 situated 

 on median side in distal part, longer, thin; seta 6 situated laterally in 

 distal part near end of suture, much smaller than 1; ventral setae 7 and 8 

 straight, short, light; seta 5 small, situated laterally near 8; seta 4 situated 

 near suture, brownish, small, thin. 



Larval case, resembling that of L. r homb icu s, made of small plant 

 fragments arranged transversely or obliquely, usually with longer pieces 

 which project laterally, sometimes with massive fragments of trees, or 

 small shells, or fragments of large shells; anterior opening obliquely 

 trunctate; posterior end covered with a membrane with a large hole. 



F*upa. Length 18—21 mm. Antennae reaching end of body. Labrum 

 brownish, near setae lighter, with rounded sides anteriorly, as in 

 L. rhombicus; seta 1 small, light, other setae brownish golden. Mandibles 

 blackish brown, resembling those of L. rhombicus in form and chaetotaxy ; 

 lateral dorsal seta much larger than ventral. Wing sheaths reaching 

 abdominal segment 5. Midlegs natatorial, with dense, relatively long setae 

 on tarsal segments 1—4; segments 1—4 of hind tarsus sparsely setose. 



Dorsal process of abdominal segment 1 dark brown, rugose; small distal 

 lobes with small spinules lateral to median depression. Holding apparatus 

 on segments 4—7; a small plate sometimes present also on segment 3; 

 hooks relatively large, their numbers as follows: IV:2; V:2+10— 16; Vl:2; 

 VII: 2; number of hooks varies within range of ± 1—3. Lateral line from end 

 of segments 5 to 8; setae dense, dark brown. Gills on segments 2 — 8. 



Anal rods with a small, black, basal seta, a larger light seta in middle, 

 and 2 black, thick, relatively large setae subapically, one behind the other. 

 Sheath of male genitalia as in L. rhombicus with large lateral lobes and 

 deeply incised apex of penis sheath (Figure 307). 



Case as in larva; anterior sievelike membrane with 30—34 holes, posterior 

 membrane with 27—30 holes. 



Mode of life and habitats. Usually in littoral vegetation of lakes, 

 rarely on open shore, on a bottom of sand, sand with stones, silt or sand 

 with detritus; species occurs mainly in vegetation, close to shore, especially 

 among sedge; isolated specimens are found in upper sublittoral to a depth 

 of 3—5 m; L.politus occurs also rarely in large clear ponds. 



Distribution. European USSR, Western Siberia, Altai, Yakutia. 

 In addition. Northern and Central Europe. 



3. Limnophilus abstrusus McLachlan 

 Lepneva, 1949:170, Figures 21-22. 



Full-grown larva. Length 16— 19 mm. Main color of head (Figure 308, A) 

 smoke brown; pattern dark, chestnut brown, blackish in some places; punctation 



231 



