Records of three anthiadine species, Plectranthias longimanus, P. nanus, and P. winniensis, from Japanese waters, with morphological and genetic comparisons (Perciformes: Serranidae)

A comparison of 68 specimens of Plectranthias (Serranidae: Anthiadinae) from Japanese waters with 85 Indo-Pacific specimens, all characterized by the fourth dorsal-fin spine longest, no branched pectoral-fin rays, two antrorse spines on the lower preopercular margin, the lateral line incomplete with fewer than 22 pored scales, and scales absent from the maxilla, revealed the former to include P. longimanus (Weber, 1913) [23 specimens, 8.5-28.4 mm standard length (SL)], P. nanus Randall, 1980 (38, 10.6-32.3 mm SL), and P. winniensis (Tyler, 1966) (7, 24.1-38.6 mm SL). Among the Japanese specimens, P. longimanus was similar to P. nanus in overall body appearance, but differed from the latter in having modally 12 pectoral-fin rays [vs. 13 in P. nanus], 15 gill rakers (vs. 17), 14 pored lateral-line scales (vs. 18), 26 or 27 scale rows in the longitudinal series (vs. 28), 8 scale rows below the lateral line (vs. 9), 3 interopercular spines (vs. spines absent), and 2 or 3 subopercular spines (vs. spines absent), a maximum body depth 34.1% (mean) of SL (vs. 28.6%), and a vertical band absent near the base of the caudal fin (vs. band present in both fresh and preserved specimens). Japanese P. winniensis clearly differed from the other two species, having 16 or 17 soft rays in both the dorsal and pectoral fins (vs. fewer than 15 rays in the latter two species), modally 16 pored lateral-line scales (vs. 14 in P. longimanus, 18 in P. nanus), subopercular spine absent (vs. 1-4 present in P. longimanus), and a greenishred body without dark blotches or bands (vs. reddish-brown body, mottled with dark blotches and bands). In addition, analyses of 12S ribosomal RNA and cytochrome c oxidase subunit I gene sequences indicated that the three species were genetically distinct from each other. In Japanese waters, P. longimanus has been recorded from the Izu Peninsula and the Izu Islands to the Koshiki Islands, mainland Kagoshima, and the Ryukyu Islands, P. winniensis having a similar distribution pattern, i.e., from the Izu Islands south to the Ryukyu Islands. Plectranthias nanus has been recorded only from island groups, including the Ogasawara, Ryukyu, and Daito islands.