Caecidotea insula, A New Species of Subterranean Asellid from Lake Erie’s South Bass Island, Ohio (Crustacea: Isopoda: Asellidae)

Three species of obligate subterranean asellids were previously known from Ohio, all assigned to the stygia Group of the genus Caecidotea: C. stygia, C. filicispeluncae, and C. rotunda. Caecidotea insula, n. sp., is described here from two caves on South Bass Island, Ottawa County, Ohio. This island is only 7 km from the Canadian border. The new species is assigned to an assemblage proposed here as the forbesi Group, which includes the epigean species C. forbesi, C. racovitzai, C. attenuata, and C. obtusa. Evidence suggests that C. insula evolved as the result of a groundwater invasion by ancestral C. forbesi during the late Pleistocene.