August, 1944 



Ross: Caddis Flies of Illinois 



59 



232 



233 



Polycentropus Larvae, Heads 



Fig. 230. — P. cinereus. 

 Fig. 231.— P. centralis. 

 Fig. 232. — P. reniotus. 

 Fig. 233. — P. interruptus. 



ent shade than background 



flavus, p. 68 



Head with spots conspicuous 4 



4. Upper part of frons long, subequal in 



length to lower portion, fig. 232; 

 hair on basal segment of anal ap- 

 pendages in irregular lateral areas. . 



remotus, p. 67 



Upper part of trons shorter than lower 

 portion, fig. 233; hair on basal seg- 

 ment of anal appendages in regular 

 rows, fig. 229 5 



5. Dorsum of head usually clouded with 



reddish brown; major pair of setae 

 of upper frons with a small pale area 



around base interruptus, p. 69 



Dorsum of head usually not clouded 

 with reddish brown; major pair of 

 setae of upper frons with a brown 

 ring around base glacialis, p. 68 



Adults 



1. Genitalia complex, with an aedeagus, 



figs. 234-248 (males) 2 



Genitalia without an aedeagus, figs. 

 249, 250 (females) 16 



2. Eighth sternite produced into a long, 



apical projection, figs. 234, 235. ... 3 

 Eighth sternite not produced into an 

 apical projection, fig. 236 4 



3. Apical projection of eighth sternite 



wide and incised on meson, fig. 234 



aureolus, p. 64 



Apical projection of eighth sternite 



narrow and pointed, fig. 235 



crassicornis, p. 64 



4. Cerci with dorsal angle produced into 



a long, down-curved, sclerotized 



needle, fig. 242 5 



Cerci without such a sclerotized proc- 

 ess, fig. 236 11 



5. Ninth sternite narrow; cerci with a 



narrow, finger-like projection from 



latero-caudal margin, fig. 242 



pentus, p. 65 



Ninth sternite wide; cerci without a 

 finger-like projection from latero- 

 caudal margin, fig. 243 6 



6. Aedeagus long and U-shaped, fig. 243 



maculatus, p. 65 



Aedeagus straight or only slightly 

 curved, figs. 244, 246 7 



7. Baso-dorsal appendage of clasper 



almost sessile, without a definite 

 stalk, fig. 244, and projecting lat- 



erad of clasper confusus, p. 65 



Baso-dorsal appendage with a definite 

 stalk so that the dark mesal point is 

 some distance from the basal part of 

 the clasper, figs. 246, 247, and not 

 projecting laterad of it 8 



8. Ventral aspect of claspers wide on 



basal portion, tapering suddenly to 



a narrow apex, figs. 245, 246 9 



Ventral aspect of claspers tapering 

 gradually or imperceptibly from base 

 to apex, figs. 247, 248 10 



9. Claspers with base wide and subparal- 



lel two-thirds of its length, the apex 

 short and digitate; filaments of cerci 

 long and sinuate, their apex curved 

 dorsad; baso-dorsal appendage of 

 clasper with a subtriangular apex 

 well differentiated from stalk, fig. 



245 elarus, p. 65 



Claspers with base wide for only one- 

 third its length, the apex long and 

 curved; filaments of cerci curved 

 ventrad and closer to basal portion; 

 baso-dorsal appendage with apex 

 smaller and merging gradually with 

 stalk, fig. 246 carolinensis, p. 66 



10. Baso-dorsal lobe of claspers long and 

 narrow, the mesal point round, the 

 entire lobe arched; aedeagus widened 

 at tip, fig. 247 pixi, p. 66 



