A New Species of Cryptoplax (Mollusca, Polyplacophora, Cryptoplacidae) Described from Southern Japan

抄録

A new chiton species Cryptoplax brunoi is described from the Ryukyu Islands, southern Japan. The new species has long been confused with a widespread Indo-West Pacific species, Cryptoplax burrowi (E. A. Smith, 1884), because of its close resemblance. It is distinguishable from the latter by having more fleshy, brownish girdle that is lacking greenish maculation, narrower tegmentum of the intermediate valves, wider, and flared articulamentum of the tail valve, and finely grooved, club-shaped dorsal spicules. Among five syntypes for C. burrowi, four syntypes in one of two lots were emphasized in Smith’s original description while the single syntype in a second lot is here identified as belonging to the new species. One of the four syntypes corresponding to the more familiar widespread species is here designated as the lectotype of C. burrowi.