Plectroninia celtica n. sp. (Calcarea, Minchinellidae), a new species of “pharetronid” sponge from bathyal depths in the northern Porcupine Seabight, NE Atlantic

Recent pharetronid sponges were regarded as relict species in tropical and subtropical waters, inhabiting cryptic habitats on coral reefs and in caves. More recent findings of a new species of the genus Plectroninia off northern Norway, with an inner fused skeleton have changed that view. Recent investigations on the sponge fauna of the “Propeller Mound”, northern Porcupine Seabight, focusing on sponges growing on the azooxanthellate cold-water coral Lophelia pertusa (Linné 1758) and Madrepora oculata Linné 1758, established the presence of a species of Plectroninia new to science. Its status as a common species within this deep-water coral habitat and the general status of the genus Plectroninia are discussed