Meso- and metathorax are almost twice as long as the prothorax 

 and markedly broader (Figure 25 8); both segments are divided into an 

 anterior and posterior part by a light transverse groove; they are covered 

 with light dashes and dots. Anterior -margin seta of mesonotum large, 

 reddish brown, that of the metanotum dark, but small and thin; the primary 

 anterior -angle setae of both segments are dark and relatively large; nearby 

 stands a small, light secondary seta; medioanal seta of mesonotum larger 

 than the anterior -angle seta, that of metanotum smaller; nearby is a thin 

 light intermediate seta; the lateral seta is small and not always present. 



The pleuron of prothorax reddish yellow in the episternal region, which is 

 separated by a deep, narrow, membranous notch from the black sclerite; 

 epimeral seta situated on a membrane small, reddish brown; trochantin brown; 

 its distal seta strong and black. There are two black pleural sclerites on 

 the meso- and metathorax (as in the whole genus Rhyacophila): 

 a longitudinal sclerite with a small seta and a transverse sclerite which 

 extends to the articular process of the coxa; epimeral seta situated on a 

 membrane, small and reddish brown (Figure 258). 



252 Legs (Figure 259) brown, short, differing little in length; forelegs more 

 massive than the others. Form, size and arrangement of the setae of the 

 legs exactly as in Rhyacophila s. str. but the setae are thinner. Claws 

 more curved and pointed. 



Abdominal segment 1 (Figures 258 and 259) shorter and slightly narrower 

 than segments 2 and 3; it seems to be connected with the metathorax; 

 segments 2 and 3 are the broadest part of the body; the abdomen tapers 

 gradually from segments 4—7; segment 8 much smaller; segment 9 

 is small and narrow as usual. The dorsum of the abdomen is 



253 brownish in fixed larvae; the light respiratory stripes form a transverse 

 K-shaped figure with minute stripes and spots laterally, and with an inter- 

 segmental interrupted row of dashes and dots. 



The gills of segments 2—8 (Figures 258—262) form a sucker-shaped 

 tubercle and a gill filament situated slightly more dorsally and anteriorly 

 and divided by a deep fold; the gill filament is conical; it is narrower and 

 slightly curved at the end; the gills of fixed specimens are white. Compared 

 with the gills of Rhy ac ophi la s. str., those of Rh. r e t r ac t a consist 

 of one filament of the dorsal branch and the stem of the ventral branch 

 without filament. 



The anterior -margin and anterior-angle setae are indistinct on the 

 dorsum of the first abdominal segment; intermediate surface seta shorter 

 and thinner than the medioanal seta; lateral seta small; anterior -margin 

 setae on the dorsum of segments 2—7 small, light and distinguished with 

 difficulty;* anterior-angle setae relatively large, brown, situated on 

 segments 2—5 in about midlength; they are displaced posteriorly on 

 segments 6—7; medioanal seta almost as long as the anterior -angle seta; 

 intermediate seta shorter and thinner; lateral surface seta small; it is 

 situated on the anterior segments at a distance from the other two setae; 

 it stands closer to the other two setae on the posterior segments. 

 Anterior -margin seta of segment 8 longer than on segment 7; the 

 anterior -angle seta stands in a row with the posterior setae near the 

 lateral surface seta which is transparent, straight, markedly longer than 



* The small setae are not shown in the figures. 



269 



