Integrative taxonomy does not support a cosmopolitan Desmophyllum pertusum: Resurrecting D. californicum and validating the genus Desmophyllum
Reef-building corals are key contributors in marine ecosystems, from warm, shallow reefs to cold, deep-water habitats worldwide. Desmophyllym pertusum (Linnaeus, 1758) is one of the most important habitat-forming cold-water corals (CWCs) and has long been considered a cosmopolitan species. Yet phylogenetic relationships within the genus, as well as its relatedness to the synonymized genus Lophelia, remain poorly understood and debated. Here, we use nuclear ultraconserved elements (UCEs) and exons, complete mitochondrial genomes, and single nucleotide polymorphism (SNP) data to show that populations of D. pertusum in the eastern and central North Pacific Ocean are genetically differentiated from those in the western and eastern Atlantic Ocean. Morphological features of specimens from the Pacific Ocean, particularly budding pattern and corallite size, match those of the previously synonymized D. californicum comb. nov., which we therefore reinstate. We also incorporated solitary Desmophyllum spp. lineages into phylogenomic analyses, including a multispecies coalescence model. Our results support the previously proposed synonymy of genera Lophelia and Desmophyllum. Taken together, these integrative taxonomic results indicate the presence of multiple Desmophyllum species beyond those currently recognized as valid. We recommend that future studies incorporate phylogenomic approaches to better delimit species boundaries and avoid grouping distinct coral species.