2026 年 52 巻 3 号 p. 121-128
A new ostracod species, Thomontocypris chongcheni sp. nov., was discovered at the hydrothermal vent fields of the Oomurodashi submarine volcano south of Izu-Oshima, Japan, based on the specimens collected using the remotely operated vehicle (ROV) Hyper-Dolphin. It represents only the second ostracod species described from a hydrothermal vent habitat in Japanese waters. The species is characterized by a combination of characters, including its smooth, subtriangular carapace, the presence of two very short setae on the antennal exopodite, an S-shaped horn-like seta on the seventh limb, and a dumbbell-shaped Zenker’s organ. The male also possesses a unique, gently curved copulatory tube resembling the rim of an ear. This finding adds to the limited knowledge of meiobenthos inhabiting hydrothermal vents in the Northwest Pacific.
