Abstract
Members of Scleraxonia Studer, 1887 are one of the most dominant megafaunal taxa in seamounts, but their diversity and spatial distribution are poorly known in the tropical Western Pacific. Among these, the family Victorgorgiidae Moore et al., 2017 is typically characterized by josephinae clubs in tentacles and a remarkable purple color and remains one of the most poorly known scleraxonian taxa currently. Victorgorgiidae contains only the genus Victorgorgia Lopez-Gonzalez & Briand, 2002 and six species. Here we describe three new species of Victorgorgia, V. fasciculata sp. nov., V. iocasica sp. nov., V. flabellata sp. nov., and re-describe V. eminens Moore et al., 2017, based on samples collected from four seamounts in the tropical Western Pacific, and evaluate their phylogenetic position using sequence data of mtMutS and COI genes. These new species are distinguished from each other and congeners by the sclerite forms and sizes, colony characters and polyp arrangement, and particularly the sclerites in the polyps and medulla are found to be most informative. Phylogenetic analyses indicate that V. flabellata sp. nov. is the sister group of V. iocasica sp. nov., and V. eminens Moore et al., 2017 showed a close relationship with Victorgorgia sp. GU563313. However, genetic divergence at the species level was found to be inadequate for differentiation of some close species. Each of the four species was found only from a single seamount, suggesting limited biological connectivity among the four seamount gorgoniians. Our study increases our understanding of the species diversity of Victorgorgiidae, and highlights the need for further research on the diversity and zoogeography of the deep-sea gorgonians.
Highlights
The suborder Scleraxonia Studer, 1887 is a group of octocorals with an axis composed of fused or unfused sclerites (Bayer, 1981; Fabricius and Alderslade, 2001; Daly et al, 2007; Devictor and Morton, 2010)
We describe three new species of Victorgorgia, V. fasciculata sp. nov., V. iocasica sp. nov., V. flabellata sp. nov., and re-describe V. eminens Moore et al, 2017, based on samples collected from four seamounts in the tropical Western Pacific, and evaluate their phylogenetic position using sequence data of mismatch repair protein − mutS − homolog (mtMutS) and coxidase subunit I (COI) genes
There is no genetic variation between V. iocasica sp. nov. and V. flabellata sp. nov., which are differentiated by the types of tentacle sclerites and the ornamentations of medulla sclerites (Figures 5– 8 and Supplementary Figures S5A, S6B,C, S7B, S9B)
Summary
The suborder Scleraxonia Studer, 1887 is a group of octocorals with an axis composed of fused or unfused sclerites (Bayer, 1981; Fabricius and Alderslade, 2001; Daly et al, 2007; Devictor and Morton, 2010). They are among the dominant megafaunal taxa in the hard-bottom environments from shallow water to the deep sea, abundant and diverse on seamounts (e.g., Genin et al, 1986; Stocks, 2004). Six families possess unconsolidated axes (Anthothelidae Broch, 1916; Briareidae Gray, 1859; Moore et al, 2017; Spongiodermidae Wright and Studer, 1889; Subergorgiidae Gray, 1859; Paragorgiidae Kükenthal, 1916), and three have consolidated axes (Coralliidae Lamouroux, 1812; Melithaeidae Gray, 1870; Parisididae Aurivillius, 1931) (Aurivillius, 1931; López-González and Gili, 2001; Crowther, 2011; Cairns and Wirshing, 2015; Figueroa and Baco, 2015; Moore et al, 2017)
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