August, 1944 



Ross: Caddis Flies of Illinois 



133 



bearing setae situated at some distance from 

 the mesal sclerite. 



Case. — Tortoise-shell-like with top piece 

 ovoid, high and convex, the bottom piece 

 forming a plate which covers all but the 

 front and back of bottom opening. Made 

 from fibrous material, opaque, sometimes 

 with other matter attached. 



Male. — Length 2.8 mm. Color and gen- 

 eral structure as given for unto. Genitalia, 

 fig. 473 : ninth segment short and stocky, its 

 dorsal portion cutting away nearly to base 

 to receive the tenth tergite ; tenth tergite 

 with a rounded internal base shaped like 

 an inverted scoop; apical portion of tergite 

 divided into many parts, conspicuous among 

 them being stylelike sclerites B, C and D, 

 spurlike J, the stout, apical hook H, and 

 the ventral lobe J' which has a small pre- 

 apical tooth; the entire structure is pro- 

 duced on each side into a sclerotized attach- 

 ment stub which is anchored to the internal 

 lateral portion of the ninth sternite; clasp- 

 ers sinuate, the base fairly wide, suddenly 

 constricted near middle to form a broad 

 shoulder bearing four dark spurs and an 

 apical flaplike portion; aedeagus simple and 

 filiform, typical for the genus. 



Female. — Similar to male in size, color 

 and general structure. Genitalia, fig. 481 : 

 eighth sternite set off distinctly from struc- 

 tures of the ninth, its apical margin fairly 

 heavily sclerotized and almost straight; the 

 segment has an internal bell-shaped struc- 

 ture whose ventral surface is fenestrate with 

 oblong and linear reticules; bursa copu- 

 latrix typical for the genus. 



Holotype, male. — Utica, Illinois, Split 

 Rock Brook: July 11, 1941, Ross & Ries. 



Allotype, female. — Same data as for 

 holotype. 



Paratypes. — Illinois: Port Byron: 

 May 14, 1942, Ross & Burks, 2S, 3 9. 



This species is related to confusa, differ- 

 ing from it in the shorter apical process of 

 the clasper, the much larger hook of the 

 tenth tergite, shorter style B, and other 

 details. 



A colony of larvae of this peculiar spe- 

 cies has been found, existing in a short 

 stretch of the spring-fed brook at Split Rock, 

 Utica, Illinois. Unique for the genus is the 

 tortoise-shell-like case and the conspicuous, 

 sclerotized plates on the tergites of the lar- 

 vae. In genitalia the adults suggest nothing 

 peculiar, very plainly being a derivative of 

 the spinosa group. In this group the larvae 



and cases are very similar to those of the 

 primitive unio group. 



Ochr atrichia confusa (Morton) 



Ithytrichia confusa Morton (1905, p. 69); cT. 



Although known only from New York 

 and Tennessee, this species may be found in 

 Illinois with future collecting. The larva 

 has not been discovered. The larva accredit- 

 ed to this species by Lloyd (19l5fl) was 

 misidentified; it was Leucotrichia pictipes. 



Oxyethira Eaton 



Oxyethira Eaton (1873, p. 143). Genotype, 

 here designated: Hydroptila costalis Curtis. 



Loxotrichia Mosely (1937, p. 165). Geno- 

 type, by original designation: Loxotrichia 

 azteca Mosely. New synonymy. 



Dampfitrichia Mosely (1937, p. 169). Geno- 

 type, by original designation: Dampfitrichia 

 ulmeri Mosely. 



The species of this genus frequent a wide 

 variety of situations, and many of them are 

 very widely distributed geographically. We 

 have taken only four species in Illinois, but 

 it is likely that others will be found in 

 future collecting. No characters have been 

 found to separate the larvae to species. 



KEY TO SPECIES 



Adults 



1. Apex of abdomen with various sclero- 



tized rods and plates (males), fig. 



485 2 



Apex of abdomen cylindrical (females), 

 fig. 494 10 



2. Eighth tergite with apico-lateral mar- 



gins produced into long, serrate 



processes, fig. 485 serrata, p. 136 



Eighth tergite without apico-lateral 

 processes, fig. 489 3 



3. Aedeagus divided at neck into two 



twisted, sclerotized filaments which 

 cross each other near apex, fig. 486 



pallida, p. 137 



Aedeagus not divided into twisted 

 filaments 4 



4. Aedeagus with prominent spiral proc- 



ess at neck, figs. 487-489 5 



Aedeagus with spiral process incon- 

 spicuous or absent, figs. 492, 493. . 7 



5. .'\pex of eighth segment toothed and 



serrate; claspers projecting, up- 

 turned and bootlike, fig. 487 



coercens, p. 137 



