taxonID	type	description	language	source
0926166CFFDDFFEEFCCB3D1FFCEF3B33.taxon	description	(Figs. 2 A – D, 3 A – C, 4 A – C, 5 A – C)	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDDFFEEFCCB3D1FFCEF3B33.taxon	materials_examined	Material examined. 6 males (24.4 × 19.5, 24.0 × 18.9, 23.7 × 18.9, 21.5 × 17.0, 19.3 × 16.0, 18.6 × 15.3 mm) (NCHUZOOL 17222), Vellar River, India, coll. M. Prema, September – December 2020; 2 males (23.4 × 18.8, 19.1 × 15.7 mm) (ZRC 2024.0599), Vellar River, India, coll. M. Prema, September – December 2020; 1 male (18.1 × 14.8 mm) (NCHUZOOL 17290), Vellar River, India, coll. M. Prema, September 2020; 1 male (24.3 × 19.5 mm) (NCHUZOOL 17291), Vellar River, India, September – December 2020; 1 female (18.9 × 15.8 mm) (NCHUZOOL 17292), Vellar River, India, coll. M. Prema, September – December 2020; 4 males (23.4 × 18.9, 21.8 × 17.3, 19.0 × 16.2, 18.7 × 15.7 mm) (NCHUZOOL 17296), Vellar River, India, coll. M. Prema, September – December 2020; 4 males (23.5 × 18.9, 21.6 × 17.6, 19.7 × 16.8, 18.8 × 15.4 mm) (ZRC 2024.0600), Vellar River, India, coll. M. Prema, September – December 2020; 4 males (19.5 × 16.5, 18.9 × 16.6, 18.4 × 16.2, 16.5 × 14.3 mm) (CASAU- 1051), Vellar River, India, coll. M. Prema, 13 November 2023; 2 males (20.4 × 16.9, 22.4 × 16.5 mm) (CASAU- 1052), Vellar River, India, coll. M. Prema, 10 November 2022; 2 males (19.4 × 16.4, 16.8 × 14.0 mm) (CASAU- 1052), Vellar River, India, coll. M. Prema, 22 September 2022.	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDDFFEEFCCB3D1FFCEF3B33.taxon	diagnosis	Diagnosis. Carapace (Fig. 2 A – C) subquadrate, almost circular, 1.2 – 1.3 times wider than long; surface granular, with scattered, short setae. Supraorbital margin (Fig. 3 A – C) slightly backward-sloping. Anterolateral margin (Fig. 3 A – C) granulated, setose, with 3 relatively well-defined teeth (including exorbital tooth). First tooth (exorbital tooth) broadly to acutely triangular; second tooth broad, lobular or subrectangular, with rounded to acutely angular tip, directed upwards and outwards; U-shaped incision between first and second teeth narrow, pronounced, deep; third tooth distinct, small, bluntly triangular, directed upwards and outwards. Front moderate in width. Eyestalk (Fig. 3 A – C) slightly curved, more-or-less uniform in width throughout its length, cornea less inflated. Male chelipeds subequal. Merus inner and outer margins with fringe of long setae. Inner surface of carpus with dense long setae; outer surface smooth. Palm short, inflated; upper margin and inner surface with thick mat of setae. Ambulatory legs (Fig. 2 A – C) long, slender. Male pleon (Fig. 4 A – C) tapering gradually toward telson, tip of telson rounded anteriorly. G 1 (Fig. 5 A – C) relatively stout; subdistal region gently tapered, short and gently curved. Habitat. Subtidal muddy bottoms of the estuaries (Kemp, 1915). In the Vellar River estuary, Tamil Nadu, India (Fig. 6 A, B), M. leptophthalmus and M. latreillei specimens were collected using fishing nets at depths of 4 – 10 m. Size. Largest male CW 24.4 mm (NCHUZOOL 17222); largest female CW 18.9 mm (NCHUZOOL 17292).	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDDFFEEFCCB3D1FFCEF3B33.taxon	distribution	Distribution. India (Kemp, 1915; Mendoza & Ng, 2007; this study). East coast of India; so far known from Chilka Lake in the north and Vellar River in the south (Fig. 1).	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDDFFEEFCCB3D1FFCEF3B33.taxon	discussion	Remarks. The type locality of M. leptophthalmus was indicated as “ Chili ” in South America (H. Milne Edwards, 1852: 160). Others have suggested that the type locality is likely not Chile, but rather India (Mendoza & Ng, 2007: 677), particularly since Macrophthalmus and Macrophthalminae are not known from the eastern Pacific (Barnes, 1967, 2010), and a synonymised species, M. gastrodes Kemp, 1915, has its type locality in Chilka Lake in Orissa, India. From this, it can even be surmised that the “ Chili ” in the original label / s of the types of M. leptophthalmus may have been a misspelling of “ Chilka ” (P. J. F. Davie, pers. comm.). Subsequent studies focusing on the region around Chile, such as Boschi (2000) and Retamal & Moyano (2010), have not provided any specimen collection data for M. leptophthalmus, with the authors basing this record solely on H. Milne Edwards’ original report (H. Milne Edwards, 1852). In contrast, apart from records in the western Pacific (which were actually M. dagohoyi, see later), M. leptophthalmus has only been reliably recorded in India (see the synonymy list above for details).	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDBFFE3FCCA3FDEFD1835AC.taxon	description	(Figs. 2 E – H, 3 D – F, 4 D – F, 5 D – F)	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDBFFE3FCCA3FDEFD1835AC.taxon	materials_examined	Material examined. Holotype: 1 male (14.9 × 13.4 mm) (NMCR 27008), subtidal mangrove mud, Abatan River Estuary, Bohol Island, Philippines, coll. Panglao 2004 Expedition, 28 June 2004. Paratypes: 1 male (13.5 × 12.1 mm) (NMCR 27009), 1 female (17.5 × 15.6 mm) (ZRC 2007.0004), subtidal mangrove mud, Abatan River Estuary, Bohol Island, Philippines, coll. Panglao 2004 Expedition, 28 June 2004. Others: 2 males (17.2 × 14.2, 15.0 × 12.5 mm), 1 female (14.0 × 11.8 mm) (NCHUZOOL 17340), Amami Island, Japan, coll. T. Yonezawa, 4 September 2024; 1 male (19.5 × 15.8 mm), 1 female (13.3 × 11.6 mm) (NCHUZOOL 17293), Yakugaki River, Amami Island, Japan, coll. T. Yonezawa, 6 October 2013; 1 male (16.2 × 13.7 mm), 1 female (13.3 × 11.6 mm) (ZRC 2024.0077), Yakugaki R., Amami Island, Japan, coll. T. Yonezawa, 6 October 2013; 5 males (24.4 × 20.3, 20.9 × 17.4, 20.6 × 16.9, 19.4 × 16.3, 17.6 × 14.7 mm), 2 females (21.2 × 17.2, 17.2 × 14.4 mm) (NCHUZOOL 17294), Wenchang, Hainan Island, China, coll. X. Zhang, 30 November 2023; 1 male (20.7 × 16.9 mm), 1 female (20.3 × 16.7 mm) (ZRC 2024.0598), Wenchang, Hainan Island, China, coll. X. Zhang, 30 November 2023; 1 male (18.9 × 16.1 mm) (NCHUZOOL 17295), Sanya, Hainan Island, China, coll. You-Qi Hao, 18 March 2023.	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDBFFE3FCCA3FDEFD1835AC.taxon	diagnosis	Diagnosis. Carapace (Fig. 2 E – G) subquadrate, almost circular, 1.15 – 1.23 times wider than long; surface granular, with scattered, short setae. Supraorbital margin (Fig. 3 D – F) distinctly backward-sloping. Anterolateral margin (Fig. 3 D – F) granulated, setose, with 3 relatively weak teeth (including exorbital tooth). First tooth (exorbital tooth) broadly subtriangular, never acutely tipped; second tooth broad, lobular or subrectangular, with rounded tip, directed upwards and outwards; U-shaped incision between the first and second teeth wide, less pronounced, shallow; third tooth relatively indistinct, small, bluntly triangular, directed upwards and outwards. Front moderate in width. Eyestalk (Fig. 3 D – F) relatively more curved, more tapering, cornea more inflated. Male chelipeds subequal. Merus inner and outer margins with fringe of long setae. Inner surface of carpus with dense long setae; outer surface smooth. Palm short, inflated; upper margin and inner surface with thick setae. Ambulatory legs (Fig. 2 E – G) long, slender. Male pleon (Fig. 4 D – F) tapering gradually toward telson, tip rounded anteriorly. G 1 (Fig. 5 D – F) relatively slender; subdistal part tapering, long and curved. Habitat. Subtidal muddy bottoms of mangrove estuaries or creeks at water depths ranging from 20 cm to 10 m (Mendoza & Ng, 2007; Kishino et al., 2011; Koyama et al., 2022; this study). On Amami Island, the habitat is a muddy slope in a mangrove area with gentle flow and minimal freshwater influence. The area remains submerged even at low spring tides, with soft, deeply deposited mud and occasional plant debris, sometimes forming a reduced (anoxic) layer (Fig. 6 C, D). In Hainan, specimens were captured using entangling nets from soft bottoms at a depth of about 10 m. Size. Largest male CW 24.4 mm (NCHUZOOL 17294); largest female CW 21.2 mm (NCHUZOOL 17294).	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDBFFE3FCCA3FDEFD1835AC.taxon	distribution	Distribution. Japan (Shikoku, Kyushu, and Ryukyu Islands), China (Hainan Island) and the Philippines (Bohol Island) (Mendoza & Ng, 2007; Kishino et al., 2011; Koyama et al., 2022; Nunobe et al., 2023; this study) (Fig. 1).	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
0926166CFFDBFFE3FCCA3FDEFD1835AC.taxon	discussion	Remarks. Since its original description (Mendoza & Ng, 2007), this species has not been recorded under this name, with only a few studies mentioning it in lists (e. g., Ng et al., 2008; Sasaki, 2023) or keys (Barnes, 2010). Based on the morphological and molecular results of our study, this species is now confirmed to also occur in Amami Island, Ryukyu Islands, Japan (Kishino et al., 2011, as “ Euplax leptophthalmus ”) and Hainan, China (this study). By extension, the record of Euplax leptophthalmus from Miyazaki Prefecture in Kyushu, Japan, should also be treated as M. dagohoyi. Although M. dagohoyi and M. leptophthalmus are very similar in morphology, they can be distinguished by differences in the carapace and male G 1 (see “ Morphological differences and variation ” in the Discussion). Molecular analyses. The analysis has revealed a number of distinct haplotypes for each species for both 16 S and COI genes (Table 1). The mean pairwise nucleotide divergences of K 2 P distances and bp differences for the COI haplotypes are shown in Table 2. K 2 P values (and bp differences) for M. leptophthalmus are 0.15 – 1.38 % (1 – 9 bp), and for M. dagohoyi are 0 – 0.61 % (0 – 4 bp). Conversely, interspecific differences between these two species range from 0.76 % to 2.48 % (5 – 16 bp). Both species differ from M. latreillei and M. barnesi by larger values of ≥ 13.51 % (≥ 80 bp). The phylogenetic analysis based on these sequences (Fig. 7) shows that M. leptophthalmus and M. dagohoyi are closely related, but the support values are not high. The two species and M. latreillei form a highly supported monophyletic group. However, the support values for a larger clade comprising this group of three species together with M. barnesi are weak.	en	Shih, Hsi-Te, , Jhih-Wei Hsu, , Jose Christopher E. Mendoza, , Mani Prema, , Xu Zhang, , Tei Kishino, , Samuthirapandian Ravichandran, Ng,, Peter K. L. (2025): On the identities of two closely related sentinel crabs, Macrophthalmus (Euplax) leptophthalmus (H. Milne Edwards, 1852) and M. (E.) dagohoyi Mendoza & Ng, 2007 (Crustacea: Decapoda: Brachyura: Macrophthalmidae). Raffles Bulletin of Zoology 73: 205-219, DOI: 10.26107/RBZ-2025-0015
