Labrum broad, relatively short; dorsal sclerite light yellow and thin; 

 its membranous margin narrow and white, with short hairs; the transparent 

 seta 1 relatively long, distinct; seta 4 only slightly longer, brownish yellow; 

 setae 2 and 5 thin and straight; seta 3 light, curved; seta 6 projecting far 

 laterally. 



(252) 



FIGURES 256-259. Rhyacophila retracta Mart.: 



256 — pronotum; 257 —base of left anterior -angle setae of pronotum; 258 —thorax, 

 abdominal segments 1—3, dorsal; 259 — metathorax and abdominal segments 1—6, 

 ventral. 



Mandibles brown (Figure 254); upper blade of left mandible without teeth; 

 serrated part of lower blade projecting, with apical and basal processes; 

 distal end of right mandible divided; basal tooth of lower blade blunt, 



267 



