Mesothorax slightly longer than metathorax (Figure 235). Setae on 

 mesonotum thin and light, anterior-margin seta of mesonotum short and 

 well marked, that of the metathorax small and thin; anterior-angle seta 

 240 light brown and short; medioanal seta longer than the others; intermediate 

 seta small and straight; curved lateral seta very small. 



FIGURES 235— 237. Rhyacophila y am an ak ensi s Iwata: 



235 —full-grown larva; 236 —mandibles, dorsal; 237 — pronotum, propleuron and base of forecoxa. 



Distal episternal sclerite of prothorax light yellow; trochantin light 

 yellow, with a narrow reddish brown border; distal seta strong, reddish 

 brown; light, thin setules situated on a membrane anteriorly (Figure 23 7). 



The rodlike sclerites of the pleura of meso- and metathorax are 

 situated obliquely; the longitudinal sclerite is thinner and longer than the 

 transverse sclerite; episternal seta small and reddish, situated in the 

 basal third of the plate; seta of epimeron situated on a membrane little 

 marked. Anterior part of the corner of each segment with a single, light, 

 sausage-shaped gill directed upward and slightly posteriorly. 



253 



