Gelasimus tetragonon (Herbst, 1790)

Shih, Hsi-Te, Wong, Kingsley J. H., Chan, Benny K. K., Nguyen, Thanh Son, Do, Van Tu, Ngo, Xuan Quang & Hsu, Pei-Yi, 2022, Branchipolynoe onnuriensis Kim & Choi & Eyun & Kim & Yu 2022, sp. nov., Zoological Studies 61 (66), pp. 1-24 : 10

Gelasimus tetragonon (Herbst, 1790) ( Fig. 4A, B )

Cancer tetragonon Herbst 1790: 257 , pl. 20(110) (type locality: unknown).

Gelasimus tetragonon – Kingsley 1880: 143, pl. 9(11); Shih et al. 2015: 213, figs. 174–181; Shih et al. 2016b: 151, 169, fig. 7F; Ng et al. 2017: 125; Sasaki 2019: 12450.

Uca tetragonon – Dawydoff 1952: 141; Yamaguchi 1994: 177, 184; S-L Yang et al. 2008: 807; Shih et al. 2010b: 11, fig. 3E, F; Chertoprud et al. 2012: 270, pl. 46C, D.

Uca (Thalassuca) tetragonon – Crane 1975: 77, 596, figs. 37D, 63A, B, 81F, 82E, pl. 13; K Sakai 1999: 38, pl. 20D (holotype).

Uca (Gelasimus) tetragonon – Ng et al. 2008: 240; Shih et al. 2016a: 66, fig. 4A, B.

Gelasimus (Mesuca) tetragonon – Rosenberg 2019: 734.

Material examined: Nha Trang: 2 òò (21.7, 23.4 mm), 3 ññ (17.4–24.0 mm) (NCHUZOOL 15124), Luong Son, Vinh Luong, coll. K. J. H. Wong and I-H. Chen, 23 Nov. 2010.

Distribution: Western Indian Ocean, India, eastern Indian Ocean and West Pacific Ocean (with eastern end of Gambier Islands, French Polynesia).

Remarks: Gelasimus tetragonon is probably one of the most widely distributed fiddler crab species, covering the entire range of IWP, from eastern Africa and the Red Sea, to Gambier Islands, French Polynesia ( Crane 1975). Along shores of western South China Sea, this species can only be found in southern Vietnam (Nha Trang) and southern Hainan (Sanya) ( Shih et al. 2010b). Type locality of Cancer tetragonon was indicated as unknown in the original description (Herbst 1790). In an attempt to locate type material of this species, Crane (1975: 80) noted which “apparently not extant” in the Herbst collection at the Zoological Museum of Berlin, subsequently designated a neotype selected among material examined by A. Milne-Edwards collected from Egypt. The neotype locality was indicated as Egypt by several later authors (e.g., Davie 2002; Shih et al. 2010a 2015). However, the holotype of C. tetragonon was eventually reported by K Sakai (1999). According to the International Code of Zoological Nomenclature ( ICZN 1999: Article 75.8), which states “If, after the designation of a neotype, the name-bearing type (holotype, syntypes, lectotype or previous neotype) of the nominal species-group taxon that was (were) presumed lost is (are) found still to exist, on publication of that discovery the rediscovered material again becomes the name-bearing type and the neotype is set aside”, the name-bearing status of the male holotype at Berlin, as reported by K Sakai (1999), must be preserved, and the corresponding type locality should be indicated as “unknown”.

Figures

Fig. 4. Dorsal view of carapace and frontal view of major cheliped. G. tetragonon (A, B, NCHUZOOL 15124, CW 23.4 mm, Vinh Luong, Nha Trang, Khanh Hoa); Gelasimus vocans (C, D, specimens not catalogued, Phu Quoc Island, Kien Giang); Paraleptuca splendida (E, F, NCHUZOOL 13448, CW 19.5 mm, Vinh Luong, Nha Trang); Tubuca acuta (G, H, NCHUZOOL 15138, CW 15.9 mm, Dong Rui, Quang Ninh).