Prosternite in form of irregularly pentagonal plate (Figure 309, b); 

 anterior part whitish in middle; lateral and posterior parts with large, 

 brownish black dots; horn long, relatively thin. Mesosternites on each 

 side in form of a thin, brownish plate, with 2 transverse rows of large 

 dark sclerotized dots behind each plate (Figure 309, C). Metasternite 

 formed by 2 lateral plates with 5—6 brown dots. 



Primary ventral setae of fore femur forming 2 large, thick, light spines, 

 posterior primary seta slightly longer, thin, dark; light, dense spinules 

 between spines at ventral margin; basal part with thin, hairlike chaetoids 

 between spinules, chaetoids as on trochanter but sparser. Both primary 

 ventral setae of mid -femur dark, moderately long, very thin, situated in 

 middle of segment. Primary ventral setae of hind femur also large and 

 dark but slightly shorter, the basal situated in middle of femur, the 2nd 

 more distally; spinules at ventral margin of mid- and hind legs slightly 

 sparser and smaller than on the forelegs. 



Abdominal segment 1 ventrally with thin, yellowish sternite of 

 characteristic form, with dark punctation (Figure 309, D). 



Gills on segments 2—7. 



Tergite of abdominal segment 9 (Figure 309, E) light brown, slightly 

 dark near anterior margin; medioanal seta and anterior -angle seta long, 

 dark brown; intermediate and lateral setae thin, short, or moderately long; 

 one or two secondary setae large, dark, situated between medioanal setae, 

 other secondary setae short or small, situated on surface or near margin. 



Sclerite "b" of anal legs blackish brown; setae as in L. rhomb icus. 

 Claw dark brown, blackish apically; dorsal denticle reddish. 



Case straight, relatively wide, made of detritus, mainly small, transversely 

 arranged particles, often with mollusk shells among the detritus. 



Mode of life and habitats. Near shore of lakes, including large 

 lakes (Lake Teletskoe). 



Distribution. USSR: Siberia, Altai, Kamchatka. In addition, Mongolia. 



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187 



4. Limnophilus marmoratus Curtis 



Struck, 1899: Figure 1 6, a-c; 1 900 : 16, 19-20, Figure 30a. - Ostwald, 

 1901 : 11 0-1 11.- Siltala, 1904c: 40-45, Figure 9.- Ulmer, 1909 : 259. - 

 Lestage, 1921 :732-733, 748.- Hanna, 1956c : 194-198. 



Full-grown larva. Length 1 8— 20 mm. Resembling L. p o 1 it u s, but 

 darker and smaller. Pattern on frontoclypeus (Figure 31 0) wide, dark, 

 black or blackish brown, reaching frontal sutures anteriorly, lighter near 

 anterior margin; median indentation of pattern absent or indistinct, barely 

 visible on dark background; longitudinal stripe wider posteriorly; 

 punctation indistinct in dark specimens; posterior angle of sclerite and 

 area near tentorial pit lighter; dorsal stripes wide, extending from anterior 

 margin to coronal suture, joining at fork; narrow, dark stripes further 

 along suture; punctation lateral to suture more distinct than on dark stripes. 

 Lateral stripes wide, with numerous dots; space between stripes dark. 

 Ventral surface uniformly dark, brownish, except a light stripe at anterior 

 margin; posterior part with light and dark dots laterally. Gula dark. 

 Setae as in Figure 310. 



233 



