A cryptic species complex of stony corals (Dendrophyllia, Scleractinia) at mesophotic depths in northern Portugal

European Coral Reef Symposium (ECRS 2024), 2-5 July 2024, Naples, Italy

Cold-water corals play a crucial role in the structuring of marine benthic communities, particularly in the deep-sea where they can form vulnerable marine ecosystems (VMEs) such as coral reefs and gardens. The genus Dendrophyllia de Blainville, 1830, comprises 31 species of brightly colored azooxanthellate stony corals, of which four are reported for the Lusitanian and Mediterranean Sea biogeographic provinces - D. alternata Pourtalès, 1880; D. cornigera (Lamarck, 1816); D. laboreli Zibrowius & Brito, 1984 and D. ramea (Linnaeus, 1758). However, the recent discovery of colonies with variable morphological characteristics in the Eastern Mediterranean has raised questions regarding the specific status of D. cornigera, a species with a wide Atlanto-Mediterranean distribution. In this study, we investigated the identity and phylogenetic relationships of Dendrophyllia specimens obtained on the northern continental shelf of Portugal as bycatch from local artisanal fisheries, at mesophotic depths. Morphological analysis and phylogenetic reconstructions performed using mitochondrial (COI) and ribosomal (ITS1, 5.8S, ITS2) markers, reveal the presence of D. ramea and an additional Dendrophyllia species in the area. This second species is morphologically similar but phylogenetically distinct from D. cornigera, supporting the idea of a species complex. Our findings call for the need of a detailed taxonomic revision and larger scale phylogenetic and phylogeographic study of this species complex in view of better delineating the status and geographic distribution, as well as connectivity (or lack thereof) between the respective populations. These findings are of even greater relevance taking into account that both D. cornigera and D. ramea are listed as VME indicator species, as well as Endangered and Vulnerable, respectively, on the IUCN Red List, warranting them a high management and conservation priority

Peer reviewed