The Polyclad Genus Pseudoceros, with Special Reference to the Indo-Pacific Region

THE OCCASION of this article is the acquisition of three species of thepolyclad genus Pseudoceros from the region of the Coral Sea. Pseudo. ceros is one of the most populous p.olyclad genera. In 1950, Marcus (1950: 84-88) listed 79 names in this genus, but the elimination of synonyms and of species that should be transferred to the genus Acanthozoon because of their papillate dorsal surface reduces the list to 72. The list, however, omits seven . Pseudoceros species described from Japan by Stimpson (1855: 380; 1857: 25-26) and acknowledged as valid by Kato (1944: 298). Marcus further left out of consideration six more of the Kelaart-Collingwood species that are figured in color by Collingwood (1876: 90-97) and that probably belong to· Pseudoceros. One of these, Burylepta ajjinis, has been refound in the Philippines and is validated as a species of Pseudoceros by Stummer-Traunfels (1933: 3566). To these must be added two species described by Kato (1944: 301), three by Marcus (1949: 86; 1950: 81; 1952: 91), and four by me (Hyman,1953: 363-370). I have further shown that Amblyceraeus luteus Plehn, 1898, must be transferred to Pseudoceros (Hyman, 1953: 366). One must further note that Stummer-Traunfels (1933 :3565) gave colored figures of 11 more species of Pseudoceros but did not name them; three of these came from the Siboga collections in the Netherland East Indies, six were taken by Semper in the Philippines, and one each came from Zanzibar and Batavia. Clearly there are at least 100 species of the genus mentioned in the literature.