Mesonotum much lighter^ grayish brown anteriorly, whitish gray 

 posteriorly with indistinct, light dots. 



Legs brown, without dots; chaetotaxy as in D.pugnax. 



Gills on segments 2 — 6; dorsally on segments 3—5, presegmental and 

 postsegmental. 



Case made of sand grains, slightly curved, with round cross section; 

 posterior opening with a membrane with a large, round, central hole. 



Mode of life and habitats. Mountain brooks and rivulets. 



Distribution. USSR: Middle Asia, highlands. 



3. Dinarthrum tchaldyrense Martynov, larva nova* 



Full-grown larva. Length 7— 8 mm. Head dark, chestnut brown 

 (Figure 613, A). Frontoclypeus with 2 pairs of small, indistinct dots 

 361 anteriorly; 2 large, light dots close together on site of transverse row 



posteriorly; 3—4 large, light, oblong dots on each side of posterior part of 

 frontal sutures, as in L.hirtum; pairs of round dots lateral to coronal 

 suture; numerous, dense, light dots behind eye; ventral side with 6—7 large, 

 transverse, oblong, light dots posteriorly, less distinct than on dorsal side. 

 Gula ovoid (Figure 613, B). 



Number and arrangement of gills of D. tchal- 

 dyrense 



Number and arrangement of gills of D. re d uc - 

 turn 



Segment 



Dorsal 



Ventral 



2 



1 





3 



1 

 1 





4 



1 

 1 





5 



1 



1 





6 



1 





Segment 



Dorsal 



Ventral 



2 



1 





3 



1 





4 



1 





5 



1 





6 



1 





7 







Large setae 9, 14, and 17 slightly shorter than in preceding species; dark 

 brown; seta 14 slightly smaller than 9; seta 15 thin, light brown, as long as 

 seta 14. 



Dorsal sclerite of labrum chestnut brown; posterior-angle sclerites 

 reddish brown; setae 1 and 2 as in D. pugnax, light, represented by a blunt 

 spine and a short, spine-shaped seta among the hairs; setae 4 and 3 light, 

 equally large: setae 5 and 6 brown, equally long, larger than the others. 



Described from a larva from the Tsakkara River in the Sevan Basin, 31 July 1960; collected by 

 A.M. Meshkova. 



451 



