Psettina tosana Amaoka 1963

Psettina tosana Amaoka, 1963

Tosa flounder; ±ãŝľ

Figure 9E; Table 12–13

Psettina tosana Amaoka, 1963a:56 (Type locality: Mimase, Kochi Prefecture, Japan). Shen, 1983:27; Shen in Shen et al., 1993:572; Shen & Wu, 2012:755.

Specimens examined. NMMB-P23211 (1, 81.5), Ke-tzu-liao, 28 Feb. 2015; NMMB-P23234 (8, 63.0–80.1), Ketzu-liao, 31 Mar. 2016; NMMB-P23309 (7, 66.1–75.8), Ke-tzu-liao, 3 Apr. 2016; NMMB-P25706 (4, 69.3–79.9), Ke-tzu-liao, 2 Apr. 2015. More specimens deposited in NMMB-P.

Diagnostic features. D 90–98; A 71–80; P 10–12; C 2+13+2=17; LLs 46–51; GR 0+6–8=6–8; vert. 10+28– 30=38–40.

Body compressed, elliptical, deepest at middle of body (40.2–46.5% SL). Head more than half of body depth (22.9–25.5% SL); front profile of head with slight concavity in front of ventral margin of upper eye; head profile smoothly convex. Snout much shorter than eye diameter. Eye diameter much shorter than upper-jaw length. Interorbital space with low ridge.

Mouth small, upper-jaw length on ocular side 6.6–7.4% SL; maxilla extending to anterior margin of lower eye. Mandibular knob very small at symphysis. Teeth on upper jaw regularly biserial; teeth on inner row larger than outer row; teeth on lower jaw uniserial. Gill rakers short, pointed at tip, not serrate on lower limb, absent on upper limb. Scales on ocular side rather large, ctenoid with row of long ctenii; cycloid on blind side. Pectoral fin on ocular side short (19.0–24.3% SL), subequal to head length; that of blind side about 2/3 of that on ocular side.

Coloration. Ocular side of body uniformly brown, 7 dark rings along dorsal, and 6 along ventral margins of body, respectively; 4 dark rings above and 2 below lateral line, respectively. Scattered small dark blotches on body; snout and both jaws pale brown. All fins pale; median fins with faint dark blotches; blind side of body uniformly milky white.

Size. Reaching 82 mm SL in Taiwan; up to 120 mm SL in southern Japan (Amaoka, 2016).

Distribution. Northeastern and southwestern Taiwan; East China Sea and southern Japan (Amaoka, 2016).

Remarks. This species resembles small specimen of P. gigantea, but can be distinguished by fewer lateral-line scales and dorsal- and anal- fin rays. Otherwise, P. tosana is smaller in size and inhabits in shallower waters than P. gigantea.