Trapezia digitalis Latreille, 1828

(Fig. 7D, E)

Trapezia digitalis Latreille, 1828: 696 .— Serène 1984: 277, fig. 185, pl. 38D.— Castro 1997a: 78, pl. 3B; 1997b: 120; 2009: 273; 2011: 80.— Galil 1987: 161, fig. 2.— Castro et al. 2004: 50.— Liu et al. 2008: 792 (list) (Hainan Island, Taiwan Island, the Xisha Islands).— Higashiji 2013: 87, fig. 2F (Ryukyu Islands).— Limviriyakul 2016: 5, fig. 4q (Taiwan Island).— Poupin 2018: 40, fig. 12J (Mayotte Island).— El-Sayed 2019: 49 (Red Sea).

Trapezia leucodactyla Rüppell, 1830: 28 .

Trapezia fusca Hombron & Jacquinot, 1852, pl. 4, fig. 17-18.—Lucas, 1853, p. 45.

Trapezia nigro-fusca Stimpson, 1860: 219 .

Trapezia ferruginea var. digitalis Paulson, 1875: 49, pl. 7, figs 5-6.

Trapezia digitalis var. typica Borradaile, 1902: 265 .

Grapsillus digitalis Rathbun, 1906: 866 .

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 female (7.59 × 5.87 mm), NS-MJJ-2022-1047; 1 pre-adult (2.38 × 2.07 mm), NS- MJJ-2022-1106; 1 male (4.56 × 3.65 mm), NS-MJJ-2022-1107; 1 female (3.22 × 2.51 mm), NS-MJJ-2022-1108; 1 male (3.02 × 2.36 mm), NS-MJJ-2022-1109; 1 female (3.62 × 3.08 mm), NS-MJJ-2022-1110; 115°29.8’E 9°54.4’N, 13 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 6 May 2022, 1 female (4.45 × 3.56 mm), NS-MJJ-2022-1316; 1 male (5.62 × 4.67 mmNS-MJJ-2022-1317); 115°31.3’E 9°52.6’N, 8 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 7 May 2022, 1 male (4.56 × 3.53 mm), NS-MJJ-2022-1375; 115°33.8’E 9°52.9’N, 8 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 9 May 2022, 1 pre-adult (2.32 × 1.75 mm), NS-MJ-2022-1616. Fiery Cross Reef, 112°58.6’E 9°38.7’N, 10 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 12 May 2022 , 1 female (4.51 × 3.54 mm), NS-YS-2022- 1012; 113°0.8’E 9°39.9’N, 10 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 14 May 2022, 4 juveniles (3.34 × 2.67 mm; 3.68 × 2.70 mm; 3.41 × 2.53 mm; 2.10 × 1.82 mm), NS-YS-2022-1172; 1 male (4.69 × 3.90 mm), NS-MJJ-2022-1192; 4 pre-adults (3.08 × 2.59 mm; 2.27 × 1.98 mm; 2.54 × 1.88 mm; 2.55 × 1.95 mm), NS-YS-2022-1234. — Zhongsha Islands: Walker Shoal, 114°29.0’E 15°55.0’N, 15 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 17 May 2022, 1 male (9.26 × 7.48 mm), 1 female (10.10 × 7.5 mm), ZS-MB-2022-1053; 17 m, coll. Wei Jiang, 6 May 2019, 1 pre-adult (3.67 × 2.90 mm), ZS105C12. Shenhu Shoal, 17 m, coll. Wei Jiang, 5 July 2020, 1 male (8.81 × 7.56 mm), ZS244C05; 20 m, 4 June 2021, 1 male (12.72 × 9.90 mm), ZS2021C9. — Xisha Islands: Yongle Island, 111°44.3’E 16°33.0’N, 10 m, coll. Shaobo Ma, Yuli Sun, Ziming Yuan, 22 May 2022, 1 female (4.51 × 3.54 mm), XS-YL-2022-1012); 1 pre-adult (2.68 × 1.96 mm), XS-YL-2002-1053. — Hainan Island: Jiajing Dao, coll. Wei Jiang, 28 March 2018, 1 female (7.76 × 5.89 mm), 100-1026-1029. All found in Pocillopora sp. ( Pocilloporidae) .

Geographical distribution. Across Indo-West Pacific and Tropical Eastern Pacific regions (Castro 2011).

Remarks. Two color patterns of Trapezia digitalis are commonly observed in pre-adults: one is the same as the adult color, which is chocolate brown, and the other has a brown anterior half and a creamy white posterior half of the carapace (Fig. 7E, NS-MJ-2022-1672).