Two new species of Cliona (Porifera, Demospongiae) boring the scleraxis of Corallium elatius from the western Pacific

Several species of boring sponges, generally belonging to the genus Cliona, were observed to bore preferentially into the scleraxis of precious red coral (Corallium rubrum) in the Mediterranean Sea. Although other species of precious corals, coming from bathyal and abyssal bottoms of the South Pacific, are affected by sponge boring activity this association has not yet been investigated. In this work, the sponges associated with many samples of Corallium elatius coming from Formosa at 150-200 m depth are examined. Two new species of Cliona, C. desimoni and C, acus, are described; Cliona desimoni is characterized by short tylostyles often reduced to spherulose spicules and by short and spiny microrabds. Cliona acus shows large oxeas, subtylostyles neddle shape and smooth spirasters. The excavations produced by these two species into coral scleraxis represent a peculiar habitat occupied by a rich endobiotic sponge assemblage composed of at least 10 species.