Systematic Review and Phylogenetic Analysis of the Nudibranch Genus Melibe (Opisthobranchia: Dendronotacea) with Descriptions of Three New Species

摘要

Three new species of the genus Melibe are described: Melibe digitata sp. nov. and M. tuberculata sp. nov. are recorded from the Philippines. Specimens of M. minuta sp. nov. have been found only from Okinawa, Japan. Specimens of Melibe engeli Risbec, 1937 are recorded and described from the Hawaiian Islands and the Philippines and an additional photo is noted from southern Japan. These represent the first published records of this species since its original description. The anatomy of an additional nine species of Melibe is re-examined. These include: M. australis (Angas, 1864), M. bucephala Bergh, 1902, M. leonina (Gould, 1852), M. liltvedi Gosliner, 1987, M. megaceras Gosliner, 1987, M. papillosa (de Filippi, 1867), M. pilosa Pease, 1860, M. rosea Rang, 1829 and M. viridis (Kelaart, 1858). Consistent anatomical differences suggest that M. pilosa and M. papillosa represent distinct species. This review of the morphological variability within the genus provides the basis for a phylogenet-ic analysis of the group. Melibe is shown to represent a monophyletic clade. Members of the genus Tethys represent the sister group of Melibe.