The scleractinian fauna of Taiwan is well-known and accounts for 316 species (Huang et al. 2014). However, most of the coral diversity surveys here have been limited to shallow waters, and benthic biodiversity below the 30-m depth limit of recreational diving remains largely unexplored. In February 2014, the starry coral Psammocora stellata (Verrill, 1866) was recorded for the first time in Taiwanese waters from a mesophotic reef off Green Island (121.47948° E, 22.63889° N). A free-living colony was observed lying on a sandy bottom, by scuba diving at 51 m depth (Fig. 1a). The brown colony was ~10 cm at its largest diameter and was composed of contorted branches with rounded tips. It was colonized by a variety of epibionts, mainly hydrozoans and bryozoans. Microscopic observations (Fig. 1b–c) showed the elongated shape of septa and multiple columellar processes, thus confirming the specimen (ASIZC0000991, Biodiversity Research Museum of Academia Sinica, Taiwan) identification based on the description given by Stefani et al. (2008). For a long time, the distribution of P. stellata has been considered as limited to Hawaii, Micronesia and the tropical Eastern Pacific (Veron 2000). Extension of the presence of this species to Australia, the Indian Ocean, the Red Sea, the Persian Gulf (see Stefani et al. 2008; but also Hoeksema and Best 1994) and now to Taiwan, suggests that this species has been overlooked or confused with other species (such as P. contigua), possibly due to the ecophenotypic variation in colony morphology (Stefani et al. 2008). In Taiwan, P. stellata could actually be restricted to mesophotic environments. This could explain why this species has gone unnoticed until now. Aside from extending the known distribution range of P. stellata and adding this species to the present knowledge of the scleractinian fauna of Taiwan, the observation presented here also draws attention to the possible importance of mesophotic benthic assemblages for the coral reef diversity in this area.
Scleractinia (Hard Corals)
SCUBA (open-circuit or unspecified)