130 



Illinois Natural History Survey Bulletin 



Vol. 23. Art. 1 



to black, with pale ring around eyes and 

 along some sutures. Abdominal tergites 

 with an inconspicuous sclerotized mesal ring. 



Adults. — Length 3-4 mm. Body and ap- 

 pendages dark brown to black with spots 

 of white on body and legs and a narrow 

 white band on front wings just before mid- 

 dle. Male genitalia, fig. 467: ninth segment 

 long, slender and flattened; claspers long, 

 symmetrical and nearly straight, each with 

 a large brush of black, peglike setae on inner 

 face at apex ; tenth tergite small, vasiform 

 and without processes. Female genitalia as 

 in fig. 478: eighth sternite with apex pro- 

 duced into a broad, emarginate lobe set with 

 fairly stout setae; internal rods straight; 

 endoskeleton apparently absent; tenth seg- 

 ment heart shaped, cerci arising near meson. 



To date we have records of this species 

 only from southern Illinois. Here it occurs 

 in several temporary streams in the Ozark- 

 ian region. The larvae usually occur in 

 large colonies, although adults are seldom 

 taken. We have many collections of mature 

 male and female pupae. There are no rec- 

 ords for other states. 



Illinois Records. — East of Aldridge: 

 May 14, 1940, Mohr & Burks, 2 larvae. 

 Alto Pass, Union Spring: May 25, 1940, 

 Mohr & Burks, S S , 3 $ , many pupae. 

 Carbondale: Clay Lick Creek, April 17, 

 1935, H. H. Ross, many larvae; May 11, 

 1935, C. O. Mohr, many larvae, 7 pupae. 

 Elizabethtown: Hog Thief Creek, May 

 10, 1935, C. O. Mohr, many larvae, 8 pupae. 

 Etherton, Jackson County: May 15, 1940, 

 Mohr & Burks, many larvae. Golconda: 

 May 11, 1935, C. O. Mohr, many larvae, 

 2 pupae; April 30, 1940, Burks & Mohr, 

 many larvae. Herod: May 10, 1935, C. O. 

 Mohr, many pupae; May 29, 1935, Ross & 

 Mohr, many pupae; Gibbons Creek, April 

 19, 1937, Ross & Mohr, many larvae; April 

 30, 1940, Mohr & Burks, many larvae and 

 pupae. Karbers Ridge: May 11, 1935, C. 

 O. Mohr, many larvae, 3 pupae. Walters- 

 burg: April 30, 1940, Mohr & Burks, many 

 larvae. Wolf Lake, Hutchins Creek: May 

 12, 1939, Burks & Riegel, 7 larvae; May 31, 

 1940, B. D. Burks, U. 



Ochr atrichia xena (Ross) 

 Polytrichia xena Ross (1938a, p. 122); c?'. 



Larva. — Length 3.5 mm. Head and tho- 

 racic sclerites dark brown, except for a pale 



ring around eyes and a small mesal pale 

 spot or stripe down the front of the head. 

 Otherwise similar to unio. 



Adults. — Size and color as for unio. 

 Male genitalia, fig. 466: ninth segment long, 

 slender and flattened; claspers long, sym- 

 metrical, curved slightly dorsad, each clasper 

 with two brushes of black, peglike setae on 

 inner face, one brush at extreme apex, the 

 other brush just beyond middle near ventral 

 margin; tenth tergite triangular, the base 

 membranous and wrinkled, the apex bear- 

 ing a large sclerotized shield which bears 

 two small peglike teeth. Female genitalia 

 indistinguishable from unio, fig. 478. 



Allotype, female. — Oakwood, Illinois: 

 May 21, 1936, Mohr & Burks. 



Known only from a few scattered locali- 

 ties in Illinois, this species is recorded chief- 

 ly from larval and pupal material. Better 

 diagnosis of the larvae shows that most of 

 the larvae I regarded as of this species in 

 1938 are in reality unio. 



Illinois Records. — Herod, Gibbons 

 Creek: May 13, 1937, Frison & Ross, 4^. 

 Muncie, Stony Creek: May 1, 1935, H. 

 H. Ross, many larvae; May 6, 1936, Ross 

 & Mohr, many larvae. Oakwood: May 1, 



1935, H. H. Ross, many larvae; May 21, 



1936, Mohr & Burks, 3^, 25. 



Ochrotrichia tarsalis (Hagen) 



Hydroptila tarsalis Hagen (1861, p. 275); cf. 

 Polytrichia conjusa Betten (1934, p. 154); 

 nee Morton. Misidentification. 



Larva. — Length 4 mm. Head and tho- 

 racic sclerites almost entirely yellow or 

 straw color, sometimes with a light brown- 

 ish tint; thoracic sclerites with distinct dark 

 brown markings along sutures; legs pale 

 with dark brown markings along sutures. 

 Case purselike. 



Adults. — Size and color as for unio. 

 Male genitalia: ninth segment short, clasp- 

 ers shoe shaped as in fig. 468, both claspers 

 very similar, long and tapering as seen from 

 ventral view; tenth tergite, fig. 471, with 

 right portion produced into a long spiral 

 process overlaid by a large plate; left process 

 stout, with two small sclerotized points and 

 a large sclerotized hook pointing mesad. Fe- 

 male genitalia, fig. 479: eighth sternite with 

 apical margin sinuate, the mesal portion 

 produced into a rounded lobe; internal rods 

 sinuate; endoskeleton large, extending the 

 full length of the segment and with the 



