Scleractinia (Cnidaria: Anthozoa) from INDEMARES 2010-2012 expeditions to the Avil,s Canyon System (Bay of Biscay, Spain, northeast Atlantic)

Twenty-eight species of scleractinian corals were collected between 55 and 2,291 m depth during INDEMARES 2010-2012 expeditions to the Avil,s Canyon System and the near continental shelf (Bay of Biscay). Most interesting species are described and all depicted. All species were already known from the northeast Atlantic, although some are seldom reported. Deltocyathus eccentricus and Flabellum chunii are northernmost records in the eastern Atlantic, and species first collected from the Bay of Biscay. From a literature review and new records given herein, 31 species of Scleractinia are known from the Avil,s Canyon System. Live specimens of six species were recorded outside their previously known bathymetric ranges in the Bay of Biscay and nearby areas, either at shallower depths (Caryophyllia sarsiae, Monomyces pygmaea, Stephanocyathus nobilis), or deeper depths (C. atlantica, C. sarsiae, Enallopsammia rostrata, Solenosmilia variabilis). Desmophyllum cristagalli has the widest bathymetric range (551-2,291 m), and Lophelia pertusa is the most widely distributed species (24 stations). Tabulating the number of live species occurring in each 100-m depth interval of the canyon system, highest species richness occurs in the 700-800-, 800-900-, and 1,400-1,500-m depth intervals (11 species). The habitat-forming species L. pertusa and Madrepora oculata were abundant in some stations building well-developed coral banks. Live colonies of the big-sized species S. variabilis and E. rostrata co-occurred at the deepest station sampled that yielded scleractinia (2,291 m).