Soft corals (Octocorallia: Alcyonacea) of the southern Ryukyu Archipelago: The families Tubiporidae, Clavulariidae, Alcyoniidae and Briareidae

Abstract

Species composition of soft corals from the Yaeyama and Miyako island groups, of Sakishima Is., located at the southern part of the Ryukyu Archipelago were studied during 1992 and 1993. SCUBA collections were carried out at 18 sites around the islands down to 30m. The collection, comprising approximately 200 specimens, yielded 45 species. The survey established two new species: Sinularia higai and S. tanakai, and in addition revealed 14 new zoogeographical records. Among the latter are Protodendron and Rhytisma species, which are the first records of these genera in the Ryukyu Archipelago. The obtained results along with a previous survey on Sesoko Is. show the genus Sinularia have the highest species diversity on the reefs, comprising 33-45% of total species number. Synthesizing the existing data for the south Ryukyu Archipelago yielded a total of 56 soft coral species (11 genera) of the families Clavulariidae, Tubiporidae, Alcyoniidae and Briareidae.Since the survey was conducted prior to the recent mass coral bleaching event (1998) in the region, it is of prime importance to monitor changes in soft coral species diversity and abundance there. Such data will indicate possible shifts in benthic community structure on the reefs and the rate of recovery.