A new family of diminutive zooxanthellate zoanthids (Hexacorallia: Zoantharia)

A new family, genus, and species of zooxanthellate macrocnemic zoanthid is described from Okinawa, Japan. The diminutive zoanthid Nanozoanthus harenaceussp.nov. occurs in sandy 'pools' upon hard substrates in coral reefs. The results of molecular phylogenetic analyses of mitochondrial 16S ribosomal DNA and cytochromec oxidase subunitI suggests that Nanozoanthidaefam.nov. is genetically close to family Microzoanthidae and Isozoanthus sulcatus at the intrafamily-suborder level. The Nanozoanthidaefam.nov.-Microzoanthidae clade is clearly highly divergent from all other known zoanthid families and from the order Actiniaria at the suborder level or higher. These results demonstrate that much high-level (e.g. above genus) diversity remains to be described within the order Zoantharia, and until such work is complete it will be difficult to completely understand their biodiversity.