A new family of stoloniferous coral (Octocorallia, Malacalcyonacea) from the Irish Continental Margin, Northeast Atlantic

The deep sea harbours diverse benthic communities of octocorals that are rarely identified to species rank, in part due to a lack of expertise and the large amount of undescribed diversity. Even in relatively well-studied areas, such as the Irish Margin in the Northeast Atlantic, new species are still being discovered. However, many of these species are large charismatic arborescent colonies. Herein we describe a new family and genus of stoloniferous coral using an integrated approach of traditional taxonomy and Ultraconserved Elements (UCEs). Primafloridae fam. nov. and Primaflorusgen. nov. has fully retractile polyps that emerge from branches originating from an encrusting stolon, and sclerites in the form of rods, sticks and boomerangs in the polyp, with additional branched spindles in the branches. Irregular plates are found in just the tentacles. Sclerites of the stolon are fused. All sclerites are tuberculated to varying degrees. One species is described, Primaflorus maxwelligen. nov., sp. nov., from scleractinian rubble habitat at 696-746 m from the Irish Continental Margin, just outside the Hovland Mound Special Area of Conservation. Genome skim libraries were sequenced and UCEs, complete mitogenomes, and partial 28S rDNA sequences were extracted. Phylogenomic inferences constructed from UCEs recovered Primafloridae fam. nov. within subordinal Clade M2 of order Malacalcyonacea, specifically as a sister lineage to a subclade comprising families Cerveridae and Melithaeidae. The sclerome and lack of a central axis of P. maxwelligen. nov., sp. nov. are sufficient to distinguish P. maxwelligen. nov., sp. nov. from members of both of those families. ZooBank: urn:lsid:zoobank.org:pub:F652BD29-0C4C-47DA-AC49-C2FD301FF8D0.