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Gills on segments 2—7; presegmental lateral gills absent, as in larva. 

 Holding apparatus on segments 3— 7, number of hooks: 111:1—3; IV: 2— 3; 

 V:2— 4 + 6-16; VI: 1-3; VII:2-3. Anal rods slightly curved at end, 

 with one seta in basal third, another in middle, the other 2 longer than 

 others, situated subapically one behind the other. Sheath of ventral 

 appendages of male genitalia large, much longer and wider than the very 

 short and narrow, bifid penis sheath (Figure 335). 



Pupal case 15—22 mm long, its ends with sievelike membranes covered 

 with small plant particles. 



Mode of life and habitats. Shallow, overgrown parts of lakes 

 and slow rivers, sometimes in open littoral, on a sandy or sandy -stony 

 bottom rich in detritus; in calm places protected from wind. Broadly 

 eurythermic; occurs not only in warm waters, but also in cold 

 Lake Teletskoe, where the temperature does not rise above 10° before June; 

 also in spring-fed ponds (the Ropshi area, Silurian Plateau). It occurs 

 mainly in autumn; hatching of adults in August, September. 



Distribution. The European USSR, Western and Eastern Siberia, 

 Altai, Sayans, Kamchatka, Northern Kazakhstan, Middle Asia. In addition. 

 Central and Northern Europe. 



8. Limnophilus decipiens Kolenati 



Struck, 1896:417. Figure 2; 1899:323-355; 1900 : 17, 21, Figures 7, 12. - 

 Ostwald, 1901:108-109.- Siltala, 1902:55-58, Figure 11.- Struck, 1903: 

 75-76, Plate II, Figure 3. - Ulmer, 1903:59-60. - Siltala, 1904c:40; 

 1907:496-497, 507-510.- Ulmer, 1909:258, Figure 388.- Lestage, 1921: 

 731, 741, 742, 744-746, Figures 256, 259. 



Full-grown larva. Length 16—21 mm. Head slightly oblong, light, 

 yellowish; stripes dark brown (Figure 336, A). Pattern on frontoclypeus, 

 as in L. rhomb icus, slightly wider anteriorly, not reaching frontal 

 sutures; light median indentation at anterior margin indistinct; a large 

 and 3—4 small dots on each side behind median pit; dark longitudinal 

 figure in posterior part relatively narrow; wedge-shaped figure formed by 

 large dots. Dorsal stripes relatively narrow, distinct in middle and laterally 

 with short, transverse rows of dots posteriorly; lateral stripes dark, 

 with dense, longitudinal rows of dots; space between stripes light, with 

 short, slightly dark bars behind eyes and near occipital foramen. Ventral 

 side broadly dark laterally in middle, with large groups of dots on light 

 background near occipital foramen. Gula yellowish brown (Figure 336, b). 



Dorsal sclerite of labrum (Figure 337) golden brown. Mandibles black; 

 left mandible with 5 teeth distally, middle tooth larger than others. 



Pronotum yellowish in middle, brown near posterior margin (Figure 338); 

 anterior part uniformly brown, groove dark brown in middle; posterior 

 margin wide, with a black, transverse stripe without median interruption; 

 posterior angle with 3 basal dots, with narrow dark stripe laterally; setae 

 black or dark brown, medioanal seta long, larger than anterior -angle seta. 



Mesonotum darker anteriorly in middle than in lateral and posterior 

 areas; posterior angle and lateral margin lighter; anterior margin with 

 dark, blackish brown stripe laterally; posterior margin narrow, black; 

 lateral margin broadly black near posterior angle; anterior -angle seta 

 long, larger than medioanal seta. 



248 



