Morphology and molecular phylogeny of three black corals (Antipatharia, Schizopathidae) from seamounts in the Western Pacific Ocean, with description of a new species

Three deep-sea black corals belonging to the family Schizopathidae, are reported from two seamounts on the Caroline Ridge in the tropical Western Pacific: Umbellapathes parva sp. nov. with depth of 1 488–1 766 m, Telopathes cf. magna MacIsaac & Best, 2013 with depth of 937–1 016 m, and Stauropathes cf. punctata (Roule, 1905) with depth of 942–1 353 m. The latter two species are the first records in the Western Pacific Ocean. U. parva sp. nov. is characterized by monopodial corallum, relatively long unpinnulated stalk with complex pinnulated branches developing from the lowermost primary pinnules and small spines. It differs from two known congeners by much smaller spines and the present of secondary pinnules. T. cf. magna MacIsaac & Best, 2013 has sparsely branched corallum, relatively long and simple pinnules arranged in subopposite or alternate pairs. S. cf. punctata (Roule, 1905) is characterized by the corallum with almost planar pinnulated branches, and pinnules arranged in subopposite pairs. Our results indicate that the corallum size and shape are variable in conspecific specimens particularly those at different growth stages. By contrast, the size of the polypar spines as well as the abpolypar spines have little variation and can be served as a main differing feature for schizopathid species. The phylogenetic analyses using nuclear internal transcribed spacer region (spanning partial 18S rDNA, ITS1, 5.8S, ITS2, and partial 28S rDNA) and two mitochondrial fragments cox3-IGR-cox1 (COI) and trnW-IGR-nad2 (NAD2) showed Telopathes, Stauropathes, and Bathypathes had close relationships, and Umbellapathes formed a sister clade with Alternatipathes.