Uca (Gelasimus) tetragonon (Herbst, 1790)

(Fig. 4A, B)

Cancer tetragonon Herbst, 1790: 257, pl. 20(110) [type locality: Egypt].

Uca (Thalassuca) tetragonon — Crane 1975: 77, figs. 37D, 63A, B, 81F, 82E, 99, pl. 13; Sakai 1976a: 605, text-fig. 332a; Nagai & Nomura 1988: 53, 1 unnumbered fig.; Shih 1994: 78, figs. 51–55.

Uca tetragonon —Takeda 1973: 9, fig. 1; Takeda 1982: 208, 1 unnumbered fig.; Ho et al. 1993: 18, figs. 2, 3, 4d; Okutani 1994a: 214, figs. 4; Yamaguchi 1994: 177, 184; Wang & Liu 1996a: 48, 3 unnumbered figs.; Hung 2000: 140 -1, figs. 430– 431; Chen 2001: 205, 2 unnumbered figs.; Ng et al. 2001: 37 [list]; Yoshigou 2001: 4, fig. 2, pl. 1F, G; Nakasone & Irei 2003: 269, fig. 30; Wang & Liu 2003: 84, figs. 87–89; Shen & Jeng 2005: 167, 2 unnumbered figs.; Katsu 2007: 84, 9 unnumbered figs.; Liu & Wang 2010: 42, 3 unnumbered figs.; Japanese Association of Benthology 2012: 215, 1 unnumbered fig.; Shih 2012b: 70, figs. 99–101; Fujita & Uyeno 2015: 95, fig. 2C, D.

Uca (Gelasimus) tetragonon —Ng et al. 2008: 240 [list]; Toyota & Seki 2014: 222, 4 unnumbered figs.

Material examined. Taiwan: 2 ♂♂ (10.6, 25.2 mm), 1 ♀ (13.1 mm), 1 ovig. ♀ (18.1 mm), 1 juv. (7.2 mm) (TMCD CHCD 476), Houwan, Pingtung, coll. H.- C. Liu, 2 Aug. 1994; 2 ♂♂ (15.0, 18.9 mm), 5 ♂♂ (12.1–20.8 mm) (TMCD CHCD 491), 4 Aug. 1994; 3 ♂♂ (13.8–24.3 mm) (NCHUZOOL 14701), Wanlitong, Pingtung, coll. S.- H. Han, Oct. 1966; 2 ♂♂ (12.8, 13.6 mm), 1 ♀ (12.4 mm) (TMCD CHCD 526), Wanlitong, Pingtung, coll. H.- C. Liu & C.- H. Wang, 23 Sep. 1994; 2 ♂♂ (21.7, 23.5 mm), NCHUZOOL 14687, Wanlitong, Pingtung, coll. J.- H. Lee, 20 Aug. 2009; 3 ♂♂ (11.6–16.7 mm), 1 ♀ (16.4 mm) (TMCD), Beijyunjei, Taitung, 21 Apr. 1993; 2 ♂♂ (25.8, 30.2 mm) (NCHUZOOL 14696), Dulanwan, Taitung, 7 Apr. 2001; 4 ♂♂ (11.1–23.7 mm), 2 ♀♀ (9.7, 12.2 mm), 5 ovig. ♀♀ (16.7–23.8 mm) (NCHUZOOL 14695), 1 ♀ (17.0 mm) (NCHUZOOL 13666), Shanyuan, Taitung, coll. W.- C. Wang, 29 May 2004; 3 ♂♂ (18.4–23.6 mm), 1 ♀ (9.2 mm) (NCHUZOOL 14697), Shanyuan, Taitung, 27 July 2014; 1 ♀ (14.3 mm) (NCHUZOOL 14693), Dulanwan, Taitung, coll. H.- T. Hung, 2 Sep. 2004 . Penghu Islands: 1 ♂ (26.1 mm) (NCHUZOOL 13304), Citou, coll. H.- T. Shih, 17 Aug. 1996; 1 ovig. ♀ (26.9 mm) (NCHUZOOL 14686), Chihsi, Siyu, coll. H.-T. Shih, 19 May 2007. Dongsha Island: 1 ♂ (26.2 mm) (NCHUZOOL 14678) , 1 ♂ (32.3 mm) (NCHUZOOL 14699), coll. Y.-C. Yang, 15 June 1997; 2 ♂♂ (21.3, 25.0 mm) (NCHUZOOL 14689), coll. D.-C. Jiang & J.-C. Fan-Jiang, 12 Sep. 2008; 3 ♂♂ (25.0– 31.7 mm), 2 ♀♀ (18.5, 31.4 mm), 1 ovig. ♀ (25.6 mm) (NCHUZOOL 14688), coll. C.-Y. Chung & Y.-H. Huang, 7 June 2011; 1 ♂ (28.2 mm) (NCHUZOOL 14692), 3 Sep. 2011; 1 ♀ (31.0 mm) (NCHUZOOL 14684), 19 Nov. 2011; 1 ♂ (19.5 mm) (NCHUZOOL 14728), 19 Nov. 2011; 2 ♂♂ (18.3, 26.6 mm) (NCHUZOOL 13664), coll. H.-T. Shih, 22 Mar. 2012; 1 ♂ (21.4 mm) (NCHUZOOL 14694), coll. H.-T. Shih, 23 Mar. 2012; 1 ♂ (19.1 mm) (NCHUZOOL 14702), coll. H.-T. Shih, 24 Mar. 2012; 1 ♂ (29.0 mm) (NCHUZOOL 14698), 22 Sep. 2012. Ryukyus: 5 ♂♂ (19.1–26.9 mm), 2 ♀♀ (25.1, 26.9 mm) (TMCD 2739), Ootomo, Iriomote, coll. H. Ota, 26 Oct. 1991.

Distribution. Western Pacific (Ryukyus, Taiwan [including Penghu and Dongsha], Hainan in China, Philippines, Malay Peninsula, Borneo, Indonesia, New Guinea, Australia), Central and South Pacific, and Indian Ocean (Thailand, Middle East, East Africa).

Remarks. The species is common in eastern and southern Taiwan, as well as on the offshore islands of Penghu and Dongsha with habitats being mainly composed of coarse sand adjacent to coral reefs (Ho et al. 1993; Shih 2012b).