A specimen collected at Okinawa Fish Market was identified as Synanceia horrida (Linnaeus, 1766) in having the following characters: 16 pectoral fin rays (vs. 18-19 in S. verrucosa, 14-15 in S. nana and 11 in S. alula), bony ridge continuously connecting eyes (vs. no continuous ridge in S. verrucosa, S. nana and S. platyrhynchus), and bony crest above eye (vs. no bony crest in S. verrucosa). This species is recorded here for the first time from Japan. Its occurrence in the Ryukyu Islands is the northernmost record of this species.
