Morphology and phylogenetic analysis of two new deep-sea species of Chrysogorgia (Cnidaria Octocorallia Chrysogorgiidae) from Kocebu Guyot (Magellan seamounts) in the Pacific Ocean

摘要

Two new species of Chrysogorgia Duchassaing & Michelotti, 1864 collected from Kocebu Guyot in the Magellan seamounts of the Pacific Ocean are described and illustrated: Chrysogorgia ramificans>sp. nov. collected from a depth of 1831 m and Chrysogorgia binata>sp. nov. collected from a depth of 1669 m. Chrysogorgia ramificans>sp. nov. belongs to the Chrysogorgia “group A, Spiculosae” with rods distributed in body wall and tentacles, and C. binata>sp. nov. belongs to the “group C, Squamosae typicae” with rods and/or spindles not present but only scales. Chrysogorgia ramificans>sp. nov. differs from congeners by its main stem with 2/5R branching sequence at the bottom forming two large bottlebrush-shaped branches with 1/3R branching sequence at the top. Chrysogorgia binata>sp. nov. is similar to C. scintillans Bayer & Stefani, 1988, but differs by its larger polyps, larger sclerites in the body wall, and different scales in the upper part of polyps. The mtMutS genetic distances between C. ramificans>sp. nov. and C. binata>sp. nov. and congeners are in the range of 0.33%–2.28% and 0.33%–2.94%, respectively, while the intraspecific distances are in the range of 0–0.16%. Molecular phylogenetic analysis indicates that C. ramificans>sp. nov. is clustered with C. monticola Cairns, 2007 and C. binata>sp. nov. is clustered with C. chryseis Bayer & Stefani, 1988, both with high support indicating close relationships.