Chaetotaxy of head and body resembling that of Arctopsychidae, rich, 

 highly differentiated; primary setae not always fully developed; some of 

 them small, thin, indistinct among the secondary setae. Secondary setae 

 numerous, highly differentiated, represented by ordinary setae resembling 

 the primary setae and by minute covering setae all over the body, and which 

 differ strongly in form and size; these setae were illustrated in detail by 

 Siltala (1907:358—359). We frequently name the small covering setae 

 "chetae" or "covering chetae" which means setae with a distinct alveolus and 

 not chetoids of the group of spines. 



Labrum with a broad membranous anterior and lateral margin; dorsal 

 sclerite yellowish, sometimes dark in some places, with long posterior- - 

 angle sclerites which are curved and reddish black at the end; membranous 

 margin with long and short hairs (hairlike spines) laterally and in the middle 

 which are different in the 2 subfamilies; sclerite also with numerous short 

 secondary setae, including covering setae in addition to the primary setae. 



Mandibles massive, with large teeth; penicillus in median depression of 

 left mandible present or absent; outer side of mandibles slightly concave, 

 with primary and secondary setae. 



Cardo, submentum and stipes with numerous secondary setae. 



Nota of all thoracic segments sclerotized; meso- and metanotum without 

 median suture; posterior margin of mesonotum with a characteristic curved 

 spot, rarely with a spot of different form; posterior margin of metanotum 

 with a small, dark, median spot, sometimes with a black dot, or spot absent. 



Abdomen with small brownish setae adpressed to the surface (absent in 

 the genus Aethaloptera). Gills present on segments 1 — 7, rarely on 

 segments 1 — 6 or 1—8, on the pleural and ventral surface; gills with a stalk 

 and filaments. 



Segment 9 or segments 8 and 9 ventrally with 2 brownish sclerites 

 separated by a narrow median membranous stripe; sclerites with dense 

 long and short covering setae. 



Anal legs long; apex of sclerite of section "b" with a narrow, dark, 

 ventrally curved plate with a dense tuft of dark setae which form a fan, 

 in addition to the articular process; this plate is small, with several setae 

 478 in the subfamily Macronematinae. Sclerite "c" relatively large, with a long, 

 strong, dark seta. Claw short, bent at a right angle, with ordinary primary 

 setae. 



Young larva. It shows primitive characters in the 1st stage and is 

 colorless; primary chaetotaxy simple; some primary setae are feathered; 

 gills absent; legs uniformly developed; claws of legs (unlike in the 2nd stage) 

 with a thin, spinelike process near the base in addition to the primary seta. 

 Sternal sclerites of abdominal segments 8 and 9 absent. 



An indistinct pattern appears on the head in the 2nd stage; secondary 

 setae and isolated ventral gills appear on abdominal segments 2 and 6; 

 the small distal tuft of long setae is already present on the anal legs. 



The coloration becomes more distinct in the 3rd stage; the number of 

 secondary setae increases; pleural gills appear and the number of ventral 

 gills increases. 



The color of the larva of the 4th stage resembles that of the full-grown 

 5th-stage larva, but the pattern is less distinct; number of gills and 

 secondary setae smaller than in the full-grown larva. 



544 



