477 



pattern, and on light background near posterior margin between dark median 

 and lateral pattern; posterior-margin area dark in middle and laterally. 



Dark median pattern of mesonotum larger than in M. longicornis; 

 large dark dots of border area fused with pattern and forming anterior, 

 middle, and sometimes posterior, processes; lateral dots of transverse, 

 curved row in middle of each half large and distinct. 



Metanotum with 2 anterior-angle setae situated on small, reddish brown 

 sclerites: a long, dark primary seta and a small, light brown, secondary 

 seta, latter shorter than in M. longicornis; medioanal seta strong, long*; 

 anterior-margin seta short. 



Pleurites of meso- and metathorax darker than in M, longicornis; 

 episternum with wide apical margin and large subapical dot, the latter more 

 distinct than in M. longicornis. 



All coxae ventrally and subventrally with large black lateral spots; 

 mid- and hind femora brownish, slightly darker than other segments; dark 

 distal stripes on femora, tibiae, and tarsi large, black, or blackish brown. 



Gills on segments 2 — 5 or 2 — 4; dorsal row only presegmental. 



Some full-grown larvae lack gills. 



FIGURE 76S 

 ventral (B) 



Mystacides sibirica Mart. Head, dorsal (A) and 



Tergite of segment 9 reddish brown, with large dark dots; setae black, size 

 and form as in M. longicornis. 



Sclerite "b" of anal legs white, with large, reddish brown dots basally; 

 setae and sclerite "c" as inM, longicornis. Claw with 2 denticles. 



Case straight, as in M . lo ng i c o rni s , slightly tapering posteriorly, 

 made of sand grains and pieces of detritus, some detritus fragments 

 arranged longitudinally and longer than case. 



Pupa. Length 8.3— 9.8 mm. Closely resembling that of M . 1 o ng i c o r ni s . 

 Spinules on presegmental plates of holding apparatus less numerous than 

 inM. longicornis (Figure 766). Median process between basal and 

 apical part of anal rods less projecting than in M. longicornis; apex of 

 rod curved and tapering, not hooked (Figure 767), 



* This seta is shown too short in Hickin (1943:71, Figure 7). 



597 



