132 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



and at the extreme apex a pointed process, 

 E. Female genitalia similar to anisca. 



The original type material from Herod, 

 Illinois, May 29, 1935, Ross & Mohr, is the 

 only known collection of this species. 



Ochrotrichia eliaga (Ross) 



Polytrichia eliaga Ross (194U, p. 57); cf, 

 9. 



Larva. — Length 4 mm. Head and tho- 

 racic sclerites dark brown to black with 

 pale ring around each eye and along some 

 sutures. Abdominal tergites with only in- 

 conspicuous sclerotized rings. Case purse- 

 like. 



Adults. — Size and color as in unio. Male 

 genitalia as in fig. 476: ninth segment 

 short and high; claspers suddenly sinuate 

 near base, the apex slightly enlarged and 

 spatulate; from ventral view the base ap- 

 pears broad, suddenly tapering to a plate- 

 like apical portion, the shoulder thus formed 

 bearing an uneven row of four to five scle- 

 rotized teeth, the extreme apex of the clasp- 

 er bearing a row of four sclerotized teeth 

 along the apico-ventral margin; tenth ter- 

 gite with long keel-like structure, and teeth 

 in processes on right side similar to arva. 

 Female genitalia, fig. 483 : eighth sternite 

 merging imperceptibly with structures of 

 the ninth segment; internal rods sinuate, 

 touching the endoskeleton and then curving 

 laterad; endoskeleton distinct, reaching 

 about two-thirds the distance to the base of 

 the segment and with the entire ventral 

 surface fenestrate with rectangular reticu- 

 lations; tenth segment as in anisca, fig. 480. 



This species is known from only two 

 states, Tennessee and Illinois. The Illinois 

 record consists of a single male collected in 

 company with a large flight of anisca, along 

 Hutchins Creek, Wolf Lake, May 31, 1940, 

 B. D. Burks. 



Ochrotrichia spinosa (Ross) 

 Polytrichia spinosa Ross (1938^, p. 121); cf . 



Larva. — Length 4 mm. Head and tho- 

 racic sclerites dark brown to black, similar 

 to eliaga, as are also the inconspicuous 

 sclerotized rings on the abdominal tergites 

 and the purselike case. 



Adults. — Size and color as in unio. Male 

 genitalia, fig. 475 : ninth segment short and 

 high; claspers evenly sinuate, the apex nar- 



rowed and slightly pointed, with a sclero- 

 tized tooth at the tip, and with a triangular 

 projection near the middle of the ventral 

 side; from ventral view the base of each 

 clasper appears broad, narrowing suddenly 

 beyond middle to a bladelike apex; at the 

 shoulder thus formed there is a small group 

 of two or three sharp, black spines on the 

 left clasper, and on the right clasper a small 

 group of similar spines just below the mid- 

 dle, and a stout spur upon this and well 

 separated from it. Female genitalia, fig. 

 484: eighth sternite merging imperceptibly 

 with structures of the ninth segment; in- 

 ternal rods curving to meet and follow the 

 endoskeleton; endoskeleton distinct and long, 

 extending well beyond the base of the seg- 

 ment and fenestrate over most of its surface 

 with rectangular reticulations. 



Allotype, female. — North Lake, Wiscon- 

 sin: June 5, 1938, Ross & Burks. 



Our Illinois records are all from a single 

 colony at Split Rock Brook (see p. 8), a 

 small, spring-fed brook, where we have col- 

 lected larvae and mature pupae. Associa- 

 tion of males and females is based on a large 

 collection of adults from a creek at North 

 Lake, Wisconsin. 



Few collections of this species have been 

 made, but these indicate a wide range: 

 Illinois, Kentucky (Harrodsburg), Okla- 

 homa (Turner Falls State Park) and Wis- 

 consin (North Lake). 



Illinois Records. — Utica, Split Rock 

 Brook: Feb. 1, 1941, Frison, Ries & Ross, 

 many larvae; June 17, 1941, Burks & Riegel, 

 4 (5 , 7 pupae, many larvae. 



Ochrotrichia arva (Ross) 



Polytrichia arva Ross (1941.^, p. 58); cf. 



Originally described from Martin Springs, 

 Tennessee, the species has not yet been taken 

 in Illinois. 



Ochrotrichia riesi new species 



Larva (mature type). — Length 4 mm. 

 Color of sclerites black or dark brown. 

 Head and thorax small but rounded; legs 

 short and stocky. Abdominal segments grad- 

 ually enlarged to beyond middle and taper- 

 ing to apex, segments separated by constric- 

 tions; each segment having an ovoid, dorsal 

 sclerite with a curious, transverse, mem- 

 branous center and lateral sclerotized spots 



