Acanthocephala from lake fishes in Wisconsin: host and seasonal distribution of species of the genus Neoechinorhynchus Hamann, 1892

r: Five species of Neoechinorhynchus are reported, not including Neoechinorhynchus robertbaueri Amin, 1985, which was described elsewhere. Of 14 species of fish infected with Neoechinorhynchus cylindratus (Van Cleave, 1913) Van Cleave, 1919, from Silver and Tichigan Lakes, Micropterus salmoides, Micropterus dolomieui and Esox lucius were the principal definitive hosts. Lepomis macrochirus may be a second intermediate host in its life cycle. Most recruitment occurred in late summer and in autumn, sexual development and breeding by spring, and growth and elimination of ripe eggs by summer. A partial overlap of generations was observed in the autumn. Neoechinorhynchus prolixoides mostly infected Erimyzon sucetta but was also found in M. salmoides, M. dolomieui, Pomoxis nigromaculatus, Stizostedion vitreum, Pimephalus promelas (all new host records) and Moxostoma erythrurum; new state record for Wisconsin. Measurements of Neoechinorhynchus prolixoides were provided and comparison is made with the original description. Extension of its binucleate lemniscus relative to anterior testis margin is not a good diagnostic character. The seasonal periodicity of N. prolixoides bore basic similarities to that of N. cylindratus but involved more juveniles, particularly in the spring, and its simultaneous growth and maturation produced the highest adult intensity index during the summer. The smaller land-locked Silver Lake was considerably more heavily populated by both species than the larger riverconnected Tichigan Lake. Both species showed significant but limited posterior migration in the intestine of their major hosts by the summer. Their intestinal distribution was compared with sites occupied by other helminth species in concurrent infections. Host sex did not affect worm burden, but size did. Neoechinorhynchus rutili (Muller, 1780) Hamann, 1892 and Neoechinorhynchus strigosus Van Cleave, 1949 were also recovered from Culaea inconstans and Catostomus commersoni, respectively. Neoechinorhynchus salmonis Ching, 1984 is reported for the first time in the U.S., from Lepomis cyanellus (new host species and family records) that was recovered earlier from the Pike River, which drains into Lake Michigan. The descriptions of Fessisentis tichiganensis from Tichigan Lake (Racine County) and of Neoechinorhynchus robertbaueri from Silver Lake (Kenosha County) by Amin (1980 and 1985, respectively) constitute the first 2 of this series of reports on acanthocephalans from lake fishes in southeastern Wisconsin. Four other species of Neoechinorhynchus are reported herein from the above 2 lakes with emphasis on the host and seasonal distribution of the more common 2, Neoechinorhynchus cylindratus (Van Cleave, 1913) Van Cleave, 1919 and Neoechinorhynchus prolixoides Bullock, 1963. The Neoechinorhynchus sp. reported by Amin (1975) from Lepomis cyanellus Raf. in the Pike River, which drains into Lake Michigan, is herein assigned to Neoechinorhynchus salmonis Ching, 1984 and discussed. A number of new host and state records are noted. Received 29 April 1985; revised 9 August 1985; accepted 21 August 1985. MATERIALS AND METHODS Seasonal parasitological collections were made from Silver Lake (Kenosha County) and Tichigan Lake and canal (Racine County) during the spring (April, early May), summer (June, July, early August) and autumn (late October, November) between 1976 and 1984. The 188-ha Silver Lake has a maximum depth of 13.4 m. It is an eutrophic land-locked lake of glacial origin lying within the lateral moraine of the Lake Michigan lobe of the Wisconsin glacier. A small outlet historically permitted the intermittent discharge of overflow waters (until dammed in 1932) into the Fox River, a tributary of the Mississippi River drainage system. Silver Lake was probably originally populated by fish and parasite faunas of Mississippi River origin. The size of the eutrophic Tichigan Lake, originally a natural lake on the above Fox River, increased to 458 ha as a result of an impoundment of the Fox River in 1830; it has a maximum depth of 19.2 m. Fishes were routinely collected and specimens processed and measured as described by Amin (1985). All measurements are in micrometers, with averages in parentheses, unless otherwise noted. Mean per host is the number of parasites recovered/number of fishes examined. The site of infection was determined in host alimentary regions as footnoted in Tables V and VIII. Juveniles are recently recruited young adults with in-