First records of the genus Sphenopus from temperate waters and lower mesophotic depths

Azooxanthellate brachycnemic zoantharians have so far only been reported from shallow depths (< 35 m) in tropical and subtropical regions. The present study reports for the first time on an azooxanthellate brachycnemic zoantharian, Sphenopus cf. exilis, from warm temperate waters. The record of this free-living, sand-dwelling species is from the mouth of Kagoshima Bay, Kagoshima, Japan. In addition, its congener S. marsupialis was observed on a sandy bottom at 114 m depth at Okinawa, Japan, which represents the first record of Sphenopus from lower mesophotic depths. These records from temperate to tropical sandy seafloors imply that free-living Sphenopus species may be much more widely and commonly distributed across the Indo-Pacific Ocean than is currently thought.