Abstract
A new boring sponge, Cliona reticulata sp. nov., is described from coral reefs of the Ryukyu Islands, southwestern Japan. This species differs from closely related taxa, such as C. aprica Pang, 1973, C. caribbaea Carter, 1882, C. orientalis Thiele, 1900, and C. tenuis Zea and Weil, 2003, primarily in its apparent inability to undergo papillary fusion and thus form incrustations on top of the excavated substratum, the lack of symbiotic dinophycaeans (zooxanthellae), and the unusually large size of the pits caused by cellular etching. A new type of thin, long and wavy spiraster found in the holotype is another distinctive character. The morphology of the substratum excavated by the sponge is also considered to be of diagnostic value. This is the second species of the genus Cliona reported from the Ryukyu Islands.
