Results of the Rumphius Biohistorical Expedition to Ambon (1990). Part 11. Doridacea of the families Chromodorididae and Hexabranchidae (Mollusca, Gastropoda, Opisthobranchia,Nudibranchia), including additional Moluccan material

Twenty-one species belonging to the family Chromodorididae and one species of Hexabranchus (Hexabranchidae) are present in the 1990 Rumphius Biohistorical Expedition (RBE) collection. The 1996 Fauna Malesiana Marine Maluku Expedition (Mal) collected 43 lots of nudibranchs, mostly chromodorids: 17 species were identified, six of which were not represented in the RBE collection. A total of 35 chromodorid species, belonging to nine genera, are described from Ambon and nearby localities. Four species are new to science, and seventeen species are recorded from Indonesian waters for the first time. Brief descriptions are given for the species which are well known, highlighting significant features, differentiating characters from similar species, and allowing recognition. A number of species are less well known and described and figured in more detail. The name Chromodoris marindica nom. nov. is proposed for Chromodoris reticulata sensu Eliot, 1904, and Farran, 1905 (not C. reticulata Pease, 1866) and C. inopinata sensu Rudman, 1973 (not C. inopinata Bergh, 1905). The monogeneric family Hexabranchidae is represented by four specimens of Hexabranchus marginatus (Quoy & Gaimard, 1832). All but three species are illustrated with colour photographs of the living specimens. Species of which the type locality is Ambon are tabulated in Appendix 1, while a list of species described as new from Indonesia, with comments, is presented in Appendix 2.