1. Group Rhy ac ophil a s. str. Dohler 



Dohler, 1950:272. 



Full-grown larva. Length 22—24 mm. Head oblong; setae described 

 under Rhyacophila septentrionis. Mandibles without apical teeth; 

 a small basal tooth only on the right mandible. Submentum with slightly 

 concave anterior margin and convex posterior margin; posterior angles 

 uniformly rounded; setae situated near the anterior angles; mentum with a 

 narrow median suture; maxillary palps thicker than galea; 2nd segment 

 markedly longer than the others. Pronotum with 2 long setae (a primary 

 and a secondary) in the depression at the anterior angle; 3rd seta (2nd 

 secondary seta) small and indistinct between the long setae. Tracheal 

 gills present on mesonotum, metanotum and abdominal segments 1 — 8; 

 they consist of a short branched stalk and filaments. Posterior margin 

 of dorsal sclerite of segment 9 with a shallow, median notch lateral to which 

 stands a long medioanal and anterior -angle seta and short, thin intermediate 

 and lateral setae between the above setae. Sclerite "b" of the anal legs 

 with a large pointed sword-shaped process; distodorsal tubercles blunt and 

 high; the basal of the 3 dorsal primary setae is long; the distal part bears 

 a short, thin seta and a long, thick seta. The claw has equally developed 

 basal and distal parts; the distal part bears 2 or 3 ventral spinules; setae 1, 

 3 and 5 are longer than the others; seta 2 is shorter; seta 8 is situated on 

 a short, blunt spinelike process. 



212 Key to Species 

 Full-grown larva 



1 (8). Posterior margin of pronotum black. 



2 (7). Head and pronotum light brown, with a distinct dark pattern. 



Dorsal stripes on head dark brown, broad; they are darker in the 

 anterior part; they extend to near the coronal suture in the 

 posterior part; they are divided along the median suture by a 

 narrow, light stripe; the space between the dorsal and lateral 

 stripes is slightly or distinctly dark, with large light, round spots 

 at the base of the setae; the gill filaments are normally developed. 



3 (4). Dorsal stripes of head dark brown, wide, darker anteriorly. The 



space between the stripes is markedly lighter than the stripes; 



ventral surface without dark dots 



1. Rh. septentrionis McL. (p. 220) 



4 (3). Head of uniform width anteriorly and in the middle; its sides are 



almost parallel in dorsal view; the space between the stripes is 

 slightly dark; ventral dots dark, numerous or absent, rarely distinct. 



5 (6). Frontoclypeus light anteriorly; the space between the stripes is 



markedly dark; dorsal and lateral stripes almost fused in dark 

 specimens; ventral dots absent or indistinct; mainly distributed in 

 northern and Central Europe 2. Rh. obliterata McL. (p. 227) 



6 (5). Frontoclypeus dark not only in the posterior part but also near 



the anterior margin; space between stripes distinct, slightly dark; 

 large dots on the ventral side, usually on a dark background; 

 Caucasus 8. Rh. subovata Mart. (p. 236) 



219 



