Morphological and molecular evidence of a new species of Melanochlamys (Gastropoda: Heterobranchia) from the Bohai Sea, China

Increasing discoveries of new species of the genus Melanochlamys Cheeseman, 1881 in the recent years indicate that the biodiversity of this group remains underestimated. Recently, several aglajid sea slugs were collected from Laizhou Bay, Shandong Province, China. Morphological observation of their external and internal anatomy revealed that they represent an undescribed species of Melanochlamys. This new species, Melanochlamys aquilina sp. nov., is closely related to Melanochlamys fukudai Cooke, Hanson, Hirano, Ornelas-Gatdula, Gosliner, Chernyshev Valdes, 2014 in body size and dark external coloration, but can be differentiated from the latter by features of both shell and male reproductive organ. Phylogenetic analyses of two mitochondrial (COI, 16S rRNA) and a nuclear (H3) genes using Bayesian inference, maximum likelihood, and species delimitation analysis also support the separation of Melanochlamys aquilina sp. nov. from its related congeners.