Abstract
A survey of octocorals belonging to the family Xeniidae collected from the coral reefs of the Ryukyu Archipelago (Japan) revealed colonies with distinct scle-rites whose microstructure justifies the establishment of a new genus, Yamazatum. A new species, Y. iubatum has been assigned to it and is described and depicted. Its fea-tures include unique sclerites with previously undocu-mented surface architecture, comprising of one or several crests and occasionally one or several furrows, different-iating it from all known species of the family Xeniidae.
