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)

Abstract

The identities of the common Indo-West Pacific and Atlantic rafting crabs which have been identified with Plagusia depressa and P. tuberculata are clarified. The type series of Cancer depressus Fabricius, 1775, is mixed, and includes specimens of Plagusia immaculata Lamarck, 1818. A lectotype is selected to maintain its current use. The lectotype of Cancer squamosus Herbst, 1790, agrees very well with what is currently known as Plagusia tuberculata Lamarck, 1818, and the two names are clearly synonymous. The lectotype of Cancer squamosus Herbst, 1790, is here designated as the neotype of Plagusia tuberculata Lamarck, 1818. The types of Plagusia orientalis Stimpson, 1858, 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.