Arnoglossus polyspilus ( Günther, 1880 )

Amaoka, Kunio & Ho, Hsuan-Ching, 2019, The lefteye flounder family Bothidae (Order Pleuronectiformes) of Taiwan, Zootaxa 4702 (1), pp. 155-215 : 163

Arnoglossus polyspilus ( Günther, 1880)

Manyspotted lefteye flounder; ŧṯ¥6ľ

Figure 1F ; Tables 1–2

Anticitharus polyspilus Günther, 1880:48 (Type locality: Kei Island, Arafura Sea, Indonesia).

Arnoglossus polyspilus: Norman, 1927:20 ; Chen & Weng, 1965:42; Shen & Wu, 2012:747.

Specimens examined. NMMB-P22241 (10, 116.8–168.7) , NMMB-P22266 (3, 150.0–155.0), Ke-tzu-liao, 21 Jan. 2015 ; NMMB-P23271 (5, 142.9–171.9), Ke-tzu-liao, 28 Feb. 2016 ; NMMB 29041 (1 male, 164 mm), Ke-tzu-liao, 18 Mar. 2018 .

Diagnostic features. D 103–114; A 81–92; P 11–13; C 2+13+2=17; LLs 71–82; GR 0–1+8–9=8–9; vert. 10+30–32=40–42.

Body elongated, greatest depth near middle part of body (36.7–42.1% SL). Head small, its length about 60–70% of body depth (25.3–27.6% SL); front of head with small concavity anterior of upper eye; head profile gentle, same in both sexes. Snout shorter than eye diameter. Rostral spine absent on tip of snout in both sexes. Eye diameter much shorter than upper-jaw length. No orbital spines in both sexes. Interorbital ridge very low, extending from anterior margin of lower eye to posterior margin of upper eye.

Mouth moderately large, upper-jaw length on ocular side 9.7–10.9% SL; maxilla extending to anterior margin of lower eye or slightly beyond it. Teeth on both jaws uniserial, several pairs enlarged anteriorly; lateral teeth on lower jaw stronger and wider spaced than those on upper jaw. Gill rakers on lower limb, long and serrated inner edge; 0 (rarely 1) gill raker on upper limb.

Scales moderately large, ctenoid with row of short ctenii; cycloid on blind side. Few anterior dorsal-fin rays more or less elongate, longer in males than in females. Pectoral fin of ocular-side small, slightly longer than half of head length, 13.1–14.8% SL; that of blind side very short. Caudal fin round, uppermost and lowermost 2 rays simple, and middle rays divided into more than 2 branches.

Coloration. Ocular side of body uniformly pale greenish brown without distinct blotches or spots, all fins uniformly pale brownish without spots. Blind side of body uniformly milky white.

Size. Reaching 172 mm SL in Taiwan; up to about 240 mm TL elsewhere ( Hensley & Amaoka, 2001).

Distribution. Northeastern, western and southwestern Taiwan; Indian and Western Pacific oceans ( Amaoka, 2016).

Remarks. This species resembles A. oxyrhynchus , A. japonicus and A. yamanakai in having many scales on the lateral line and serration on the edge of the gill rakers. It differs however from the latter two species in having the maxilla not extended to below middle of lower eye, several anterior rays of dorsal fin elongated in males and the two uppermost and lowermost rays of the caudal fin unbranched.

Figures

FIGURE 1. A–B. Arnoglossus japonicus, NMMB-P23187, male 121.0 mm SL (A) and female, 110.2 mm SL (B). C. A. macrolophus, NMMB-P 23204, male, 81.1 mm SL. D–E. A. oxyrhynchus, NMMB-P23317, male, 148.0 mm SL (D) and female, 171.1 mm SL (E). F. A. polyspilus, NMMB-P29041,164 mm SL. G. A. tenuis, NMMB-P25684, 64.5 mm SL. H. A. yamanakai, NMMB-P25685, 95.0 mm SL.