531 



XI. Family SERICOSTOMATIDAE Stephens 



Full-grown larva. Medium-sized, 15.0— 16.5 mm long. Head and pronotum 

 chestnut brown. Head relatively wide, slightl}^ shorter than wide; fronto- 

 clypeus as in Brachycentridae, long, narrow; a longitudinal ridge laterally 

 in anterior part dorsal to eye; gula short, wide, fused in some genera 

 with large, lateral sclerites. 



Pronotum with projecting anterior-angle processes with primary anterior - 

 angle seta at apex. Mesonotum light, short, slightly sclerotized in anterior 

 part. Metanotum membranous or with anterior tergites in form of small, 

 sclerotized dots. Xumerous, dense secondary setae in anterior part of 

 pronotum and mesonotum. 



Forelegs short; midlegs and especially hind legs long; coxae, femora 

 and tibiae of all legs with numerous secondary setae. 



Lateral line replaced by small, sclerotized dots on segments 3—8. Gills 

 on segments 1—8, with 1—2 or 3—5 filaments. 



Anal legs short, thick: area "b" slightly sclerotized only laterally and 

 ventrally, with numerous secondary setae dorsally. 



Claw with short, distal part, with a large, dorsal and 2 smaller denticles. 



Case made of sand grains, in form of a wide tube, slightly curved, smooth, 

 gradually tapering posteriorly. 



The larva passes 6-7 stages (Siltala, 1907:524-526; Kielsen, 1942: 

 262—263, 428—429) which differ in size, chaetotaxy, form of gills (which appear 

 in stage 3), number of sclerotized dots on sides of abdominal segments, and 

 other characters. 



Pupa. Length 9— 15 mm.. Setae of anteclypeus relatively long, thicker 

 and longer than on labrum; mandibles wide distally, with coarsely serrated 

 median blade. Tarsi (including mid -tarsi) without natatorial setae, or 

 mid-tarsi with distinct natatorial setae, fore tarsi with sparse setae. Anal 

 appendages in form of thin rods with moderately long setae. 



Case as in larva; both ends with a membrane with a slitlike hole. 



Mode of life and habitats. Running water, often in slowly 

 running or almost stagnant overflows of springs. 



Distribution. European part of USSR including Caucasus; Maritime 

 Territory (isolated records). In addition, Europe, Africa, southwest Asia, 

 Iran, Japan. North and South America. 



Key to Genera 

 Full-grown larva 



1 (2). Gula well differentiated, wide, pointed posteriorly; gular suture 



distinct, with short, single part; metanotum entirely membranous . . 

 1. Notidobia Steph. (p. 663) 



2 (l). Gula fused with large, lateral sclerites; gular suture absent; 



sclerites behind gula fused; metanotum with a small, sclerotized 



dot on each side anteriorly 2. Sericostoma Latr. (p. 672) 



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