Phylogenetic Diversity of the Cold Water Octocoral Paragorgia arborea (Linnaeus, 1758) off the East Coast of Canada

Commonly called “bubblegum coral’, Paragorgia is a genus of cold-water gorgonian coral that has a broad global distribution and is eurybathic from depths of meters to kilometers. Such ecological breadth, however, may be confounded by the presence of cryptic species. In this study we compare the genetic distances of various Paragorgia spp. across their distribution and depth range along the Canadian mid-Atlantic margin using 18S ribosomal DNA sequences. Morphometric and 18S evidence show that although appearing similar, only one species of cold-water Paragorgia, called P. arborea, predominates in this region. However, 18S evidence from corals collected at deep depths located at one site, called the Stone Fence, indicate that a significant amount of divergence exists and other species may also be present. Such new light provides a need for further genetic testing using alternative methods (e.g. microsatellites), which could reveal new lineages that may have considerable ecological and/or taxonomic importance.