First Japanese Records of the Flounders Pseudorhombus elevatus and P. quinquocellatus (Teleostei: Paralichthyidae) from Okinawa Island, Ryukyu Islands

Abstract

Pseudorhombus elevatus Ogilby, 1912 and P. quinquocellatus Weber and de Beaufort, 1929 (Teleostei: Paralichthyidae) are newly recorded from Japan, based on 35 and two specimens, respectively, from Okinawa Island, Ryukyu Islands. Although both species have previously been recorded from Taiwan, no Japanese records are known to date. Pseudorhombus elevatus is characterized, and readily distinguished from Japanese congeners, by numerous minute teeth on both jaws, three dark blotches along the straight section of the ocular-side trunk lateral line, and dorsal- and anal-fin ray numbers. Pseudorhombus quinquocellatus resembles P. pentophthalmus Günther, 1862 and P. oculocirris Amaoka, 1969, all sharing five dark ocelli on the ocular-side body (two pairs of ocelli above and below the lateral line plus a single ocellus on the posterior portion of the lateral line). However, the former is characterized by strong caniniform teeth on both jaws (vs. no strong caniniform teeth in P. pentophthalmus and P. oculocirris); fewer lower gill rakers (9–11 in Japanese specimens) (vs. 15–21); and two dark skin flaps along the gill opening below the pectoral-fin base (vs. absent). The status of the type specimens of P. quinquocellatus was also considered, all three being regarded as syntypes, in the absence of a formal lectotype proposal. New standard Japanese names, “Maru-ganzō-birame” and “Niten-ganzō-birame,” are proposed for P. elevatus and P. quinquocellatus, respectively, the name “Itsutsume-ganzō” now being referred to P. megalops Fowler, 1934.