and thin; anterior and posterior seta almost of the same length; ventral 

 setae shorter; all setae dark brown. Tarsus of hind legs longer and much 

 thinner than tibia; tarsus of the midlegs not so long; all 4 setae are short, 

 thin, brown, of almost the same length. Basal seta of the claw of the mid- 

 legs as on the forelegs but shorter; basal seta of the claw of the hind legs 

 very short, in form of a small spinule which is thick at the base. 



Abdominal setae blackish brown or brown. The anterior-margin seta 

 on abdominal segments 1—8 is small; anterior-angle seta is small, shorter 

 than the medioanal seta; secondary anterior -angle seta very small, usually 

 hardly marked; intermediate and lateral setae situated close nearby at 

 some distance from the medioanal seta; intermediate seta slightly longer 

 than the lateral seta; the anterior -angle seta on the 8th segment is displaced 

 to the middle of the segment. 



The dorsal sclerite of segment 9 is of a characteristic form, with a broad 

 median notch on the posterior margin, concave sides and large lateral and 

 posteriorly-directed lobes of the posterior angle; the sclerite has a dark 

 brown anterior margin which is lighter in the middle; it extends also to 

 the long ribbon-shaped anterior-angle processes which surround the 

 segment laterally and partly ventrally. Anterior -angle setae small, reddish 

 yellow and situated posterior to the margin; 4 setae near the posterior 

 margin of the lobes: a long black anterior -angle seta on a process of the 

 posterior angle of the sclerite, and a short dark seta; medioanal seta 

 strong; at some distance from it there is a similar short but thin inter- 

 mediate and lateral seta which are situated closer to the angle seta. 



The anal legs (Figure 248) differ markedly from those of the group 

 Rhyacophila s. str. Part "b" is short; the dorsolateral sclerite of 

 part "b" is brownish yellow, with a broad, blackish brown median and basal 

 border; the basoventral hook of the sclerite is differentiated sclerite with 

 a long black basal part and a curved red end which enters into the notch 

 of the basoventral angle of the sclerite; the ventral plate near the hook is 

 triangular, with a straight, light short seta. The oblique groove of the 

 dorsolateral sclerite runs from the base of the basoventral hook to the 

 subapical point of the dorsal median margin of the sclerite, dividing the 

 247 sclerite into two unequal parts, an anterior and a posterior part. The 

 groove perpendicular to the oblique groove is absent. The postero- 

 lateral margin of the sclerite forms a rounded, broad process which is 

 directed posteriorly; dorsal to this process in the curve formed by the 

 margin, a small round sclerite with a long curved sword-shaped process. 

 This process is thus not a distal process of sclerite "b, " as in Rhyaco- 

 phila s. str., but a separate sclerite; unlike the true sword-shaped 

 process of Rhyacophila s. str., the "spurious sword-shaped" process 

 of the anal leg of R h. i m p a r is rodlike, irregularly cylindrical; its 

 cross section is round; it is bluntly pointed posteriorly. The dorso- 

 distal part of sclerite "b" has a black median border and a dark groove; 

 the distal tubercle is a high, posteriorly open fold on the margin of the 

 sclerite which is without a complete apex, and is well marked in species 

 of Rhyacophila s. str. but hardly marked in this species. Lateral to 

 this groove are two setae one behind the other; unlike full-grown larvae of 

 Rhyacophila s. str., both setae are long, as in the young larvae of the 



261 



