Tetraloides nigrifrons (Dana, 1852)

(Fig. 6A–C)

Tetralia glaberrima nigrifrons Dana, 1852: 83 .

Tetraloides nigrifrons .— Galil 1986a: 72, figs. 1A, B.— Galil & Clark 1988: 149, figs. 1E, 3E, 4E, J, 5B, 6E.— Castro 1997a: 72, pl. 1F; 1997b: 115; 1999b: 104; 2003: 443; 2009: 279; 2011: 79 (list).— Castro et al. 2004: 32, pl. 2B.—Castro & Titelius 2008: 323.— Ng et al. 2008: 184 (list).—Poupin & Juncker 2008: 34, fig. 15b.— Limviriyakul 2016: 4, fig. 4n, o.— Maenosono 2017: 48, fig. 2B, D, 10C, D, 11B (the Ryukyus).

Tetralia heterodactyla lissodactyla Serène 1984: 285, fig. 189, pl. 42C.

Tetralia nigrifrons f. lissodactyla Serène & Pham, 1957: 118, fig. 3D–F, pl. 1.

Material examined. Nansha Islands: Mischief Reef, 115°32.5’E 9°55.7’N, 11 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 5 May 2022, 1 pre-adult (4.32 × 3.94 mm), NS-MJJ-2022-1099; 115°33.8’E 9°52.9’N, 8 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 9 May 2022, 1 male (8.57 × 8.32 mm), 1 female (10.26 × 8.59 mm), NS-MJ-2022-1672, in Acropora digitifera ( Acroporidae); 1 pre-adult (2.47 × 2.02 mm), NS-MJ-2022-1678, in Acropora digitifera ( Acroporidae); 115°34.4’E 9°53.5’N, 8 m, 11 May 2022, 3 juveniles (4.21 × 3.74 mm; 3.92 × 3.63 mm; 2.40 × 2.10 mm), NS-MJ-2022-1872. Fiery Cross Reef, 112°58.9’E 9°39.5’N, 3 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 13 May 2022, 1 pre-adult (3.45 × 3.21 mm), NS-YS-2022-1120; 1 male (7.71 × 6.86 mm), 1 female (8.70 × 7.39 mm), 2 pre-adults (3.37 × 3.18 mm; 2.47 × 2.17 mm), NS-YS-2022-1130; 113°0.8’E 9°39.9’N, 10 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 14 May 2022, 1 pre-adult (4.14 × 3.56 mm), NS-YS-2022-1286, in partially dead Acropora sp. ( Acroporidae) reef.— Hainan Island: Xin Cun, coll. Xianqiu Ren, 21 December 2007, 1 male (7.02 × 6.21 mm), 3071. Jia Jing Dao, coll. Wei Jiang, 28 March 2018, 1 female (), 100-1036-1037. Found in Acropora sp. ( Acroporidae) unless otherwise noted.

Geographical distribution. Across Indo-West Pacific region. Known from Johnston Atoll, not from the Hawaiian Islands (Castro 2011).

Remarks. Both color patterns of Tetraloides nigrifrons previously reported (Limviriyakul 2016) were recorded in the South China Sea this time (Fig, 6A, NS-YS-2022-1130; Fig. 6C, NS-MJ-2022-1672).