Zoanthid (Cnidaria: Anthozoa: Hexacorallia: Zoantharia) species of coral reefs in Palau

Palau is world famous for its relatively pristine and highly diverse coral reefs, yet for many coral reef invertebrate taxa, few data exist on their diversity in this Micronesian country. One such taxon is the Zoantharia, an order of benthic cnidarians within the Class Anthozoa (Subclass Hexacorallia) that are commonly found in shallow subtropical and tropical waters. Here, we examine the species diversity of zoanthids in Palau for the first time, based on shallow-water (<35 m) scuba surveys and morphological identification to create a preliminary zoanthid species list for Palau. Our results indicated the presence of nine zoanthid species in Palau (Zoanthus sansibaricus, Z. gigantus, Palythoa tuberculosa, P. mutuki, P. heliodiscus, Palythoa cf. toxica, Epizoanthus illoricatus, Parazoanthus sp., Microzoanthus kagerou), apparently slightly more than have been recently observed in nearby Guam, Saipan, and the Ogasawara Islands. Additionally, it appears that some zoanthid species that have been observed to be co-occurring in the fringing reefs of Okinawa may inhabit different locations in the better developed reefs of Palau.