August, 1944 



Ross: Caddis Flies of Illinois 



71 



eral features as in fig. 262: ninth sternite 

 narrowed on ventral margin and produced 

 on meson into a low, sharp hump ; tenth 

 tergite short, semimembranous, and divided 

 at apex into just a pair of short approxi- 

 mate points; cerci broad, rounded at apex 

 with a long, curved sclerotized hook arising 

 from ventral mesal corner; claspers, fig. 

 263, appearing narrow from lateral view, 

 the extreme base produced into a hump, the 

 posterior face wide, slightly convex, with 

 a wide, lateral, setate area, the apical mesal 

 corner produced into a long, slender, sclero- 

 tized rod curved dorsad; aedeagus some- 

 what tubular with a pair of dorsal sclero- 

 tized rods and with a cushion of short, black 

 spines at apex. 



Female. — Size 7.5 mm. In color and gen- 

 eral structure similar to male. Eighth ster- 

 nite with lateral lobes large and ovate; 

 bursa copulatrix very similar to that in 

 fig. 264. 



Holotype, male. — Blue Mountain Lake, 

 Adirondack State Park, New York: June 

 19, 1941, Frison & Ross. 



Allotype, female. — Same data as for 

 holotype. 



Paratypes. — New York. — Same data as 

 for holotype, 5$, 1$. Lima: June 19, 

 1941, Frison & Ross, 2$ . 



New Hampshire. — Woodstock: June 

 21, 1941, at light, Frison & Ross, 19. 



This species is closely related to vestitus, 

 differing in the male in the large, expanded 

 lateral lobe and the elongate mesal lobe of 

 the apex; the female differs little in the 

 shape of the bursa copulatrix. 



Although not yet taken in Illinois, the 

 species is so widely distributed to the north 

 and northeast that it can be expected in the 

 state in future collecting. 



Cyrnellus Banks 



Cyrnellus Banks (1913, p. 88j. Genotype, 

 by original designation: Cyrnellus minimus 

 Banks. 



Only one North American species, mar- 

 ginalise is known for this genus. The im- 

 mature stages have never been discovered. 

 The significant generic characters for this 

 complex (which includes Nyctiopliylax) have 

 not been worked out clearly, but I am fol- 

 lowing Mosely (1934a) in assigning mar- 

 ginalis to Cyrnellus. Future association of 

 adults and larvae will help to clarify the 

 status of these genera. 



Cyrnellus marginalis (Banks) 



Nyctiophylax marginalis Banks ("19301^, p. 

 231); d^. 



Cyrnellus zernyi Mosely (1934rt, p. 142); cf. 



Larva. — Unknown. 



Adults. — Length 4.5-5.5 mm. Color 

 various shades of brown ; antennae, legs 

 and venter much paler. Male genitalia, 

 fig. 265: tenth tergite semimembranous and 

 subquadrate; cerci lanceolate, with a short, 

 ventral, styliform process; claspers long and 

 nearly straight, the apex with a sharp, large, 

 black mesal triangle. Female genitalia, fig. 

 266, with parts weakly sclerotized; eighth 

 sternite short, slightly carinate between lat- 

 eral lobes, which are large, approximate on 



Fig. 265. — Cyrnellus marginalis, male gen- 

 italia. A, lateral aspect; B, ventral aspect of 

 claspers. 



Fig. 266. — Cyrnellus marginalis, female gen- 

 italia. 



