y/f/-, 0^75 Vol. 75, pp. 207-214 28 August 1962 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON A NEW CRAYFISH OF THE PROPINQUUS GROUP OF THE GENUS ORCONECTES FROM THE OHIO DRAINAGE SYSTEM IN WEST VIRGINIA (DECAPOD A: ASTACIDAE) By Horton H, Hobbs, Jr. and J. F. Fitzpatrick, Jr. Smithsonian Institution; Department of Biology, University of Virginia A precise definition of the Propinquus Group has never been accomphshed, and adequate data are not presently available to delimit accurately the range of variation within the group. There seems no reason to doubt that the new species described below, however, has its closest affinities with Orconectes pro-pinquus sanborni (Faxon, 1884: 128), O. p. propinquus (Girard, 1852: 88), O. p. jeffersoni Rhoades, 1944: 123, O. ohscurus (Hagen, 1870: 69), O. erichsonianus (Faxon, 1898: 659), O. illinoisensis Brown, 1956: 163, and O. virginiensis Hobbs, 1951: 122, an assemblage that has been designated the Propinquus Group. This new subspecies is found well within the range of the group; indeed, its present range is surrounded by that of O. p. sanborni and O. obscurus, and although it is described as a subspecies of propinquus, collections are entirely inadequate to dehneate the area of inter gradation. The evidence that such an area exists is in the variation observed in specimens collected in Roane and Summers Counties, West Virginia (see Vari-ations ) . The distinctive featiure of this crayfish is the presence of a caudal eminence on the caudal surface of the mesial process of the first pleopod of the male. This eminence is so prominent that a cursory examination would result in the conclusion that it is actually comparable to one of the terminal elements (Hobbs, 1940: 56). Only one other member of this genus, O. quadruncus (Greaser, 1933: 10), a member of the Hylas 30— Proc. Biol. Soc. Wash., Vol. 75, 1962 (207) SMITHSONMAN „Mn-* « iwsiiiuiioN AUG2 8J982
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