A set of seven dredge hauls, between 195-215 m and 655-660 m deep on the NW slope of Gran Canaria (Canary Islands, Spain), recovered 15 000 specimens belonging to 295 species of molluscs. Of these, 254 are identified at the species level. Only 47 species, totalling 867 specimens, were live collected, which amounts to 84% of the species and 94% of the specimens represented only by shells. The dredges DW 133 (shallowest) and DW 130 (deepest) hold the highest number of species and abundance, representing about 90% of the material. Fifty-one species are new records for Canarian waters; of these, 23 are new for Spanish waters overall and three are the first reference in eastern Atlantic waters. Another 13 species, in the genera Mikro Warén, 1996, Discaclis Moolenbeek & Warén, 1987, Mucronalia A. Adams, 1860, Marginella Lamarck, 1799, Dentimargo Cossmann, 1899, Prunum Herrmannsen, 1852, Microvoluta Angas, 1877, Spirotropis G.O. Sars, 1878, Gymnobela Verrill, 1884, Mitromorpha Carpenter, 1865, Orbitestella Iredale, 1917 and Liostomia G.O. Sars, 1878, are described as new, most of them from the deepest haul at 655-660 m. Anatoma richardi (Dautzenberg & Fischer, 1896) is restored as valid species and the identification of Canarian specimens as Anatoma tenuis (Jeffreys, 1877) is disputed. Ancistrobasis lavaleyei Hoffman & Freiwald, 2017 is synonymized with A. reticulata (Philippi, 1844). Pleurotomella megalembryon (Dautzenberg & Fischer, 1896), type species of Azorilla Nordsieck, 1968, is assigned to Teretia Norman, 1888; Teretia strongyla (Dall, 1927) is synonymized with T. megalembryon, and Azorilla with Teretia. Pleurotoma teres Reeve, 1844 is selected under ICZN Art. 70.3.2 as type species of Teres Bucquoy, Dautzenberg & Dollfus 1883 and of its substitute name Teretia, discarding therefore Pleurotoma anceps Eichwald, 1830.
Canary Islands, species richness, discovery rate, Mollusca, bathyal, new records, new synonymies, new combinations, new species