Nanozoanthus (Cnidaria: Anthozoa: Hexacorallia: Zoantharia: Nanozoanthidae) outside of tropical and subtropical waters

Abstract

Two specimens of the zooxanthellate zoantharian Nanozoanthus aff. harenaceus Fujii and Reimer, 2013 are reported from Hakamagoshi, Kagoshima, Japan (31°35′N, 135°35′E). They represent the first record for the genus from temperate waters and from Japan outside of the Ryukyu Islands. The collected specimens, although clearly Nanozoanthus, differ in coloration, number of tentacles, and Symbiodinium density in the tentacles, from the only described species of the genus, N. harenaceus Fujii and Reimer, 2013, which is known only from Okinawa-jima Island, Japan. Additionally, acquired cytochrome oxidase subunit I (COI) sequences from the two specimens were identical to previously reported sequences of Nanozoanthus sp. from western Australia. Based on these combined morphological and molecular results, the specimens were identified as an undescribed species, Nanozoanthus aff. harenaceus. This northward extension of Nanozoanthus’ range demonstrates that this genus is not limited to subtropical and tropical waters as has been previously reported. They may also be found in a wider range of environments than assumed, as all earlier records are from carbonate substrate in coral reef environments and not from volcanic rock as in the current report. Due to its very small polyp size and somewhat cryptic nature, Nanozoanthus may be more widely spread than has been thought, and future research should examine other temperate locations in the Indo-Pacific.