The Perlesta placida (Hagen) complex (Plecoptera : Perlidae) in Illinois, new state records, distributions, and an identification key

Perlesta placida (Hagen), a complex of perlid stoneflies in eastern and cen tral North America, currently includes 17 described species. Large collecti ons of this genus exist at the Illinois Natural History Survey,;and, as par t of an effort to update the status of stoneflies in Illinois, all adult Il linois specimens were reexamined. Perlesta decipiens (Walsh) and P. golcond a DeWalt and Stark were previously recorded from Illinois, and, with the ad dition of six new state records, the total number of Perlesta known from Il linois is now eight. The latter include P. cinctipes (Banks), P. mr. teaysi a Kirchner and Kondratieff, P. lagoi Stark, P. nelsoni Stark, P. shubuta St ark, and P. xube Stark and Rhodes. For all species but P. cinctipes, ranges are greatly increased from either the southeastern states or the north-cen tral Plains region. Other midwestern states are likely to harbor a speciose assemblage of Perlesta. Distributions and associated ecological conditions suggested a wider range of pollution tolerance than is currently known fro m published literature. A key to males, females, and eggs is provided to ai d with regional identification of Perlesta.