. Bulletin. Natural history; Natural history. 412 Illinois Natural History Survey Bulletin Vol. 33, An. 4 and May in Iowa (as O. iowaensis, Phillips 1980), and eggs and young in April-June in Michigan (Pearse 1910; Creaser 1931). Females with eggs and young may be as small as 16 mm CL (Crocker 1957; Berrill 1978). Eggs are spherical and average about mm in diameter. The ratio of males to females among recent Illinois collections is 334:335. The largest specimen collected during the present survey is a CL female; the largest male is a form I. Van Deventer (1937) and Brown (1
. Bulletin. Natural history; Natural history. 412 Illinois Natural History Survey Bulletin Vol. 33, An. 4 and May in Iowa (as O. iowaensis, Phillips 1980), and eggs and young in April-June in Michigan (Pearse 1910; Creaser 1931). Females with eggs and young may be as small as 16 mm CL (Crocker 1957; Berrill 1978). Eggs are spherical and average about mm in diameter. The ratio of males to females among recent Illinois collections is 334:335. The largest specimen collected during the present survey is a CL female; the largest male is a form I. Van Deventer (1937) and Brown (1955) each recorded a 40-mm male; Cralley (1932) recorded a 90-mm TL (about 45-mm CL) male and a 90-mm TL female from Champaign County. O. propinquus is omnivorous, feed- ing on plant materials and insect larvae (Bovbjerg 1952). Orconectes rusticus (Girard) (Fig. 145) Cambarus rusticus Girard 1852 Cambarus juvenilis Hagen 1870 Description.—Rostrum excavated; no median carina; long acumen; margins thick, concave, terminating in spines. Carapace flattened dorsoventrally, with cervical spines; suborbital margin smooth. Areola moderate, narrowest part about 10-15 percent of length. Chelae large, heavily punctate; palm with two rows of tubercles on mesial margin. Form I gonopod with an an- gular (90° to axis of gonopod) shoulder on dorsal surface, terminating in two long elements: a sclerotized central projection curved at its tip, and a slight- ly shorter unsclerotized mesial process. Dorsally green brown to rust red; often a large red spot surrounded by light brown on side of carapace; fingers of chelae with red tips, subdistal black bands. Close relationships to O. rusticus are not readily apparent. Species often confused with, and at times considered related to, O. rusticus include O. for- ceps, O. placidus, O. putnami, O. spinosus, and until synonymized with. Fig. 146.—Presumed native distribution of Orconectes rusticus. O. rusticus by Bouchard (1977), O. juvenilis. Distrib
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