On the identities of the rafting crabs Cancer depressus Fabricius, 1775, Cancer squamosus Herbst, 1790, Plagusia immaculata Lamarck, 1818, and Plagusia tuberculata Lamarck, 1818 (Crustacea : Decapoda : Brachyura : Plagusiidae)

The identities of the common Indo-West Pacific and Atlantic rafting crabs w hich have been identified with Plagusia depressa and P. tuberculata are cla rified. The type series of Cancer depressus Fabricius, 1775, is mixed, and includes specimens of Plagusia immaculata Lamarck, 1818. A lectotype is sel ected to maintain its current use. The lectotype of Cancer squamosus Herbst , 1790, agrees very well with what is currently known as Plagusia tubercula ta Lamarck, 1818, and the two names are clearly synonymous. The lectotype o f Cancer squamous Herbst, 1790, is here designated as the neotype of Plagus ia tuberculata Lamarck, 1818. The types of Plagusia orientalis Stimpson, 18 58, were examined and the name is a also junior synonym of P. squamosa. The identity of Plagusia immaculata Lamarck, 1818, a species very close to and often confused with P. tuberculata, is clarified and a neotype designated.