seta anterior to the medioanal seta and near the anterior angle. Sides 



of segment with 2 large, blackish brown, thick setae (primary lateral setae), 



473 a long anterior seta and a shorter posterior seta on a small yellow sclerite; 

 2 wide, light yellow, thin sclerites separated by a narrow median stripe, 



on the ventral side; they are densely covered with covering setae of 2 types, 

 large, massive, brownish yellow, setuliform setae with long, thin ends, 

 interspersed with small, light setae; thick, black setae of varying length 

 near the posterior margin of the sclerites. 



Anal legs long; section "a" broad and short; section "b" longer; dorso- 

 lateral sclerite light yellow, extending partly to the ventral side at the base; 

 basal margin reddish brown. Dorsal side of sclerite without covering setae, 

 with a row of thin, moderately long, sparse setae at the inner margin; 

 2 long, thick, primary setae dorsally, above the claw; a row of strong, dark, 

 setae which are short in the basal part, distally and subventrally along the 

 margin; a longitudinal row of thin, golden brown setae which are denser 

 and longer in the apical part, in the middle of the outer side. Distal margin 

 of sclerite "a," unlike in the other larvae of Annulipalpia, with a narrow, 

 brownish black plate covered with long golden brown setae which form a 

 dense fan-shaped tuft, in addition to the articular process. Articular process 

 asymmetrical; its median branch with a narrow, blackish brown outer margin 

 with a process in the middle which has a thin end which surrounds the plate 

 at the base of the fan-shaped tuft from the ventral side. Sclerite "c" brown, 

 trapezoidal, with a strong black seta in the mediodistal angle. 



Claw (Figure 673) relatively small, dark brown, bent at a right angle; 

 membranous transverse stripe narrow; basal part short. Dorsal side with 

 the short seta 1 and the long seta 2 near the transverse stripe; seta 6 on the 

 outer side; inner side with seta 3; long setae 8 and 7 thick, light, situated 

 ventrally; seta 8 longer, curved, reaching end of claw; outer side 

 subventrally, with the dark seta 5; inner side with the light yellow seta 4; 

 both setae small. 



Mode of life and habitats. Running water, on stones and other 

 objects; predacious, building capturing chambers with nets with regular 

 quadrangular meshes; feeding on plankton and benthic animals. Mainly 



474 occurring in rivers and rivulets with many rapids, including large rivers; 

 they have been recorded from rivers and rivulets in the basin of lakes 

 Onega and Ladoga, and also from the Neva, Sviri and Pechora rivers and 

 rivulets; they are widely distributed in Siberia, in the Biya and Yenisei 

 rivers. Adults fly in large numbers (Lepneva, 1948a). 



Distribution. North and northeast of the European USSR, West and 

 East Siberia. In addition, northern Europe, Mongolia, North America. 



2. Arctopsyche palpata Martynov, larva nova 



Full-grown larva. Length 18.5— 19.0 mm. Head (Figure 674) darker than 

 in A. ladogensis; main color reddish yellow; dots black; covering setae 

 smaller and sparser; primary thick setae black or brownish black. Fronto- 

 clypeus less broad, with less deep lateral indentations. Dark longitudinal 

 median stripe of sclerite uniformly broad, not narrowing in the middle, 

 slightly rounded posteriorly. Margin of sclerite dark near the clypangulus 



539 



