August, 1944 



Ross: Caddis Flies of Illinois 



281 



KEY TO SPECIES 



1. Apex of abdomen with a complex set 



of clasping organs, fig. 932 (males) 



Apex of abdomen with a pair oi dorsal 



plates, fig. 937 (females) 



2. Apex of tenth tergite sharp and ap- 



pearing pointed from both lateral 

 and caudal view, fig. 932 



2 

 6 



Figs. 937-939. 



italia. 



939 



INCISUS 



-Hesperophylax, female gen- 



Apex of tenth tergite appearing round- 

 ed from either lateral or caudal view, 

 or both, figs. 934, 935 4 



Cerci with apico-ventral corner pro- 

 duced into a long, narrow finger, fig. 

 933; silver streak ot front wings con- 

 spicuous and bright 



magnus Banks 



Cerci with apico-ventral corner much 

 less produced, fig. 932; silver, in- 

 conspicuous consimilis Banks 



Ninth segment with lateral area short, 



anterior angle wide, fig. 936 



incisus Banks 



Ninth segment with lateral area 

 longer, anterior angle less obtuse, 

 fig. 934 5 



5. Caudal aspect of tenth tergite wide, 



the lateral projections long and 

 angulate, the membranous caudal 



area short, fig. 934 



occiden talis Banks 



Caudal aspect of tenth tergite nar- 

 rower, the lateral projections shorter 

 and trapezoidal, the membranous 



caudal area longer, fig. 935 



designatus, p. 183 



6. Tenth segment with lateral projec- 



tions scarcely developed, fig. 937. . 



occidentalis Banks 



Tenth segment with lateral projec- 

 tions forming definite wide flanges, 

 figs. 938, 939 7 



7. Tenth tergite with lateral projections 



occupying about a third of ventral 



aspect, fig. 938 designatus, p. 183 



Tenth tergite with lateral projections 

 occupying nearly two-thirds of ven- 

 tral aspect, fig. 939 incisus Banks 



Limnephiliis nogus new species 



Most closely related to pacificus, this spe- 

 cies is readily characterized by the long 

 tenth tergite and cerci, and the curious 

 pointed process of the claspers, fig. 940. 



Male. — Length 15 mm. Color tawny, 

 with irregular darker brown markings on 

 antennae, body and legs ; wings tawny with 

 a dark stigmal spot, a dark line on cord, and 

 other irregular dark areas variable in na- 

 ture. Macrochaetae of head and thorax 



Fig. 940. — Limnephilus nogus, genitalia. 

 Male: A, lateral aspect; B, aedeagus. Fe- 

 male: C, ventral aspect. 



