First Report of Costacopluma Collins and Morris, 1975 (Decapoda: Brachyura: Retroplumidae) from the Eocene of Alabama, U.S.A.

Nine specimens of retroplumid crabs collected from the late early or early middle Eocene Tallahatta Formation in southern Alabama form the basis for description of a new species, Costacopluma grayi. The discovery confirms the extension of the range of the genus into the Eocene and represents the first occurrence ofCostacopluma in the United States. As a result of the geologic range extension, the genus is now known to be contemporary with two other retroplumid genera, Retrocypoda, and Retropluma.