taxonID	type	description	language	source
C4481C7DFFF6FFD5FF30FDD4FBDCEB80.taxon	type_taxon	Type species. Clistocoeloma balansae A. Milne-Edwards, 1868, by monotypy.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	description	(Figs. 1 A – C, 5 A, B, 6 D, 9 A – D)	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	materials_examined	Type material. Lectotype: male (18.6 × 17.0 mm) (ZMH K 4188), Upolu, Samoa, no other data.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	diagnosis	Diagnosis. Carapace subquadrate, nearly as wide as long; postfrontal lobes distinct, divided by longitudinal grooves, median pair broad, prominent, distal pair less distinct, not divided (Fig. 1 A). Inner orbital angle distinct, rounded, with convex outer margin, gap absent between tip of inner orbital angle and frontal margin (Fig. 1 C). Anterolateral margin of carapace straight, smooth, external orbital angle less pronounced; posterolateral margin slightly convex. Chelipeds dorsal surface of dactylus of chela with 16 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Fig. 5 A), each tubercle on dorsal surface of movable dactylus with small median chitinous granule (Fig. 5 A). Single longitudinal pectinated ridge with 27 – 30 chitinous comb-like tubercles on dorsal surface of chela, distal end of ridge with granules; row of 8 granules behind pectinated ridge on ventral surface of palm (Fig. 5 A); inner surface of palm granulated, with single vertical row of 8 granules in adult males (Fig. 5 B). P 5 merus relatively short, wide, merus length approximately 0.44 times width (Fig. 6 D). G 1 slightly curved, distal region slightly wide; chitinous tip relatively wide, short; tip with dense tufts of setae, single row of plumose setae on exterior margin; chitinous tip visible when denuded (Fig. 9 A – D).	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	description	Description. Carapace subquadrate, nearly as wide as long; covered with coat of short setae, among which stands small tufts of setae resembling tubercles; carapace smooth when denuded. Postfrontal lobes distinct, divided by longitudinal grooves, median pair broad, prominent, distal pair less distinct, not divided (Fig. 1 A). Inner orbital angle distinct, rounded, with convex outer margin, no gap present between tip of inner orbital angle and frontal margin (Fig. 1 C). Anterolateral margin of carapace straight, smooth, external orbital angle less pronounced; posterolateral margin slightly convex. Entire margin of carapace covered with dense, short setae. Antenna short. Antennular fossa transverse. Third maxilliped with merus rounded. Epistomal margin narrow (Fig. 1 C). Chelipeds equal or subequal in size; large, robust in adult male; outer surface of palm smooth when denuded; dorsal surface of carpus covered with small tufts of setae resembling tubercles, smooth when denuded; dorsal surface of dactylus of chela with 16 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Fig. 5 A), each tubercle on dorsal surface of movable dactylus with small median chitinous granule (Fig. 5 A); single longitudinal pectinated ridge with 27 – 30 chitinous comb-like tubercles on dorsal surface of chela, distal end of ridge with granules; row of 8 granules behind pectinated ridge on ventral surface of palm (Fig. 5 A); inner surface of palm granulated, with single vertical row of 8 granules in adult males (Fig. 5 B). P 2 – P 5 covered with dense coat of setae, with small tufts of setae resembling tubercles, longer setae on dorsal and ventral margins of entire leg except dactylus; dactylus shortest, with sharp tip (Fig. 1 A); P 5 merus relatively short, wide, merus length approximately 0.44 times of width (Fig. 6 D). Male thoracic sternum covered with short setae, smooth when denuded; sternites 1 and 2 fused, with suture between fused sternites 3 and 4; sternopleonal cavity extends to edge of sternites 1 and 2. Male pleon short, wide, long setae fringed margins of pleon; somite 3 widest; telson slightly broad, triangular with convex margins, rounded tip (Fig. 1 B); male pleonal locking mechanism absent, without tubercle on sternite 5. G 1 slightly curved, distal region slightly wide; chitinous tip relatively wide, short; tip with dense tufts of setae, single row of plumose setae on exterior margin; chitinous tip visible when denuded (Fig. 9 A – D). G 2 shorter than G 1, slightly curved, tip rounded. Female characters not known.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	discussion	Remarks. The original description by A. Milne-Edwards (1869) was inadequate by modern standards and no figure was provided. He did not indicate how many specimens he had but the measurements for one specimen from Upolu was listed; no type was designated. Subsequently, De Man (1879) mentioned that the male specimen from the “ Museum zu Hamburg ” was send to him by Dr. Pfeffer to examine, and that it is the “ Original-Exemplar ” of A. Milne-Edwards from Upolu. De Man (1898: pl. 29, fig. 30 b – d) subsequently figured the chela of this male specimen. Crosnier (1965: 56) incorrectly assumed that the type was in Paris when he commented that “ le type S. villosum, qui devrait se trouver au Muséum national d’Histoire naturelle de Paris, paraît avoir disparu ”. The present type specimen matches the descriptions, measurements and figures provided by A. Milne-Edwards (1869) and De Man (1879, 1898) very well and we are confident that it is the type of S. villosum A. Milne-Edwards, 1869. As we are not sure if A. Milne-Edwards (1869) had only one specimen, the specimen we have on hand is considered syntypic and is here designated the lectotype. One of the old labels with the specimen states that the lectotype specimen was from the Godeffroy Museum. Based on the eight sales catalogues of Godeffroy Museum that were published between 1864 and 1881 by curator J. D. E. Schmeltz, the species was listed once in catalogue V in 1874 (see Bieler & Petit 2012). The Godeffroy Museum catalogue number of the specimen listed, Sesarma villosa, (see Schmeltz 1874: 76) matches the catalogue number on the label for the lectotype of C. villosum. Tesch (1917) noted that Sesarma (Holometopus) villosum might be a species of Clistocoeloma because of the pattern of setae described for the species, although he did not formally transfer it there. Serène (1968) listed the species under Sesarma (Holometopus) while indicating that there is a photographed specimen in the “ Institute of Oceanography of Nhatrang, Vietnam ”. The actual locality and collection information for the photographed specimen from the collection in the Vietnamese institute is not known and its identity cannot be confirmed. Ng & Liu (1999) noted that S. villosum should be in the genus Clistocoeloma but did not provide any explanation. Sesarma villosum was then briefly discussed by Rahayu & Takeda (2000: 40) before Davie (2002: 221) formally transferred the species to Clistocoeloma, citing McNeill’s suggestion (1968: 79). Komai et al. (2004: 41, 42) briefly discussed the generic assignment of this species in Clistocoeloma, following Davie (2002: 220). This species has been widely recorded from the IWP, i. e., Sumatra (De Man 1897, 1898), Caroline Islands (Rathbun 1907), New Guinea (Tesch 1917), Philippines (McNeill 1968), Taiwan (Li et al. 2019), Japan (Komai et al. 2004; Yuhara et al. 2017; Takakura & Komai 2019), and South Korea (Lee et al. 2010), but comparison of the morphology of the specimens from these localities shows that these specimens are of a different species, and is here described as new (see Clistocoeloma nobile n. sp.) Records of C. villosum from Nosy Be, off Madagascar (Crosnier 1965; Lenz 1910), Tuléar, Madagascar (Crosnier 1965), and Kenya (Schubart et al. 2006) are shown to be a different species. Various specimens from that region have been examined and the species clearly differs from C. villosum, and is more similar in morphology to C. suvaense and C. nobile n. sp. The morphological differences are also supported by DNA sequence differences (unpublished data) and the new species will be described in a separate study by the first author together with S. Cannicci (pers. comm.). Ecological notes. Little is known about this species except that the specimens were collected from mangroves.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF6FFD7FF30FCA0FC2EEE90.taxon	distribution	Distribution. Known for certain only from Upolu, Samoa (type locality).	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	description	(Figs. 2 A, 3 A – F, 4 A – C, 5 C, D, 6 A – C, 8 A, B, 9 E – H, 10 A – H)	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	materials_examined	Type material. Holotype: male (21.0 × 18.8 mm) (BPBM 3976), Suva, Fiji, no collection data. Other material examined: Fiji: 1 male (18.8 × 16.9 mm) (ZRC 2022.0985), river mouth, Navaca mangrove, Taveuni Island, Fiji, 16 ° 05 ’ 19 ” S 179 ° 05 ’ 48 ” E, coll. B. Y. Lee, S. Choy & B. Rashni, 26 July 2019. — 1 male (17.8 × 16.3 mm) (ZRC 2022.0986), mangrove at Suva Point Beach, near My Suva Picnic Park and Suva City Council Park, Fiji, 18 ° 00 ’ 28 ” S 178 ° 02 ’ 42 ” E, coll. B. Y. Lee & B. Rashni, 22 July 2019. — 1 male (12.1 × 10.9 mm) (ZRC 2022.0987), Bure Bure mangrove, Naqai Creek, near Naqai Bridge, Taveuni Island, Fiji, 16 ° 04 ’ 28 ” S 179 ° 05 ’ 16 ” W, coll. B. Y. Lee, S. Choy & B. Rashni, 25 July 2019. — 2 males (13.7 × 12.2 mm, 12.5 × 11.4 mm), 1 female (13.3 × 11.9 mm) (ZRC 2022.0988), river mouth, Navaca mangrove, Taveuni Island, Fiji, 16 ° 05 ’ 19 ” S 179 ° 05 ’ 48 ” E, coll. B. Y. Lee, S. Choy & B. Rashni, 26 July 2019. — 2 males (17.1 × 15.5 mm, 15.2 × 14.2 mm), 2 ovigerous females (16.6 × 15.0 mm, 16.2 × 14.5 mm), 1 female (18.7 × 17.0 mm) (ZRC 2022.0989), mangrove at Suva Point Beach, near My Suva Picnic Park and Suva City Council Park, Fiji, 18 ° 00 ’ 28 ” S 178 ° 02 ’ 42 ” E, coll. B. Y. Lee & B. Rashni, 22 July 2019. Samoa: 1 male (16.2 × 14.3 mm) (ZRC 1973.11.2.490) Upolu, coll. Godeffroy Museum.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	diagnosis	Diagnosis. Carapace slightly wider than long, almost square; postfrontal lobes distinct, divided by longitudinal grooves; median pair broad, prominent, nearly equal in proportion; distant pair broad, prominent, nearly equal in proportion (Figs. 2 A, 3 A, 4 A). Anterolateral margin of carapace with distinct external orbital angle, blunt second tooth blunt separated by distinct shallow groove from external orbital tooth; posterolateral margin convex (Figs. 2 A, 3 A, 4 A). Inner orbital angle present, truncate, slight gap between inner orbital angle and frontal margin (Figs. 3 C, 4 C). Chelipeds dorsal surface of dactylus of chela with 22 – 27 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Figs. 3 E, 5 C); absent or weak granules in female and juveniles; presence of single longitudinal pectinated ridge with 33 – 36 chitinous comb-like tubercles on dorsal surface of chela; row of 9 – 11 granules behind pectinated ridge on chela (Figs. 3 E, 5 C); inner surface of palm granulated, with single vertical row of 6 – 10 granules in adult males (Figs. 3 F, 5 D); absent in females and juveniles. P 5 merus relatively short, wide, length approximately 0.39 – 0.46 times width (Fig. 6 A – C). G 1 straight, distal region relatively wide; chitinous tip wide, short; tip with dense tufts of setae, single row of plumose setae on exterior margin; chitinous tip visible when denuded (Figs. 9 E – H, 10 A – H). Female vulvae with central operculum, ovate, slightly protruded; sternal vulvar cover slightly raised above operculum (Fig. 8 B).	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	description	Description. Carapace slightly wider than long, almost square; covered with dense coat of setae, with small tufts of setae resembling tubercles; carapace margin fringed with dense, short setae; carapace smooth when denuded. Postfrontal lobes distinct, divided by longitudinal grooves; median pair broad, prominent, nearly equal in proportion; distant pair broad, prominent, nearly equal in proportion (Figs. 2 A, 3 A, 4 A). Anterolateral margin of carapace with distinct external orbital angle, blunt second tooth blunt separated by distinct shallow groove from external orbital tooth; posterolateral margin convex (Figs. 2 A, 3 A, 4 A). Inner orbital angle present, truncate, slight gap between inner orbital angle and frontal margin (Figs. 3 C, 4 C). Antenna short. Antennules folding transversely. Third maxilliped with merus relatively ovate. Epistomial margin relatively narrow (Figs. 3 C, 4 C). Chelipeds subequal in size; large, robust in male; outer surface of palm smooth when denuded; dorsal surface of carpus with small tufts of setae resembling tubercles, smooth when denuded; dorsal surface of dactylus of chela with 22 – 27 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Figs. 3 E, 5 C); absent or weak granules in female and juveniles. Presence of single longitudinal pectinated ridge with 33 – 36 chitinous comb-like tubercles on dorsal surface of chela; row of 9 – 11 granules behind pectinated ridge on chela (Figs. 3 E, 5 C). Inner surface of palm granulated, with single vertical row of 6 – 10 granules in adult males (Figs. 3 F, 5 D); absent in females and juveniles. P 2 – P 5 with dense coat of setae, with small tufts of setae resembling tubercles, longer setae on dorsal and ventral margins except distal portion of dactylus (Figs. 2 A, 4 A); P 5 merus relatively short, wide, length approximately 0.39 – 0.46 times width (Fig. 6 A – C). Male thoracic sternum covered with short setae, smooth when denuded; sternites 1 and 2 fused, with suture between fused sternites 3 and 4; sternopleonal cavity extends to edge sternites 1 and 2. Male pleon wide, stout, long setae fringed pleon margin; somite 3 widest; somite 6 with curved edge; telson wide, dome-shaped (Figs. 3 B, D, 4 B); male pleonal locking mechanism absent, without tubercle on sternite 5. G 1 straight, distal region relatively wide; chitinous tip wide, short; tip with dense tufts of setae, single row of plumose setae on exterior margin; chitinous tip visible when denuded (Figs. 9 E – H, 10 A – H). G 2 shorter than G 1, slightly curved, tip rounded. Female pleon rounded, relatively wider than long; telson dome-shaped (Fig. 8 A). Vulvae with central operculum, ovate, slightly protruded; sternal vulvar cover slightly raised above operculum (Fig. 8 B). Colouration. Chelipeds pale yellow fingers with pale orange to reddish palm (Fig. 2 A). In life, entire crab covered in thick layer of mud.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	discussion	Remarks. Clistocoeloma suvaense was described by Edmondson (1951) based on one male and one female specimen collected from a reef in Suva Harbour. He compared it with other species that were recognised in Clistocoeloma at the time, i. e., C. balansae. C. merguiense and C. tectum (Rathbun, 1914). Clistoceoloma villosum was not treated or discussed as it was not in the genus at the time. Edmondson (1951) actually had three specimens from the Bishop Museum, two of which were collected from Suva Habour, Fiji, while one male specimen was collected from a Samoan reef. While Edmondson (1951) was certain that the two Fijian specimens belonged to his new species, he was more doubtful about the Samoan one; noting that the latter had no distinct lobes on the anterolateral margins (lobes present on the anterolateral margins of C. suvaense s. str.) and the dorsal surface of the dactylus of the male chela with 16 granules (with 25 granules in C. suvaense s. str.). We have not examined Edmondson’s (1951) Samoan specimens, but his observations match exactly what is known for C. villosum, we believe they are conspecific. Clistocoeloma suvaense is known with certainty only from its type locality, although there is one specimen also from Samoa (see below) and published records from Singapore (Wee & Ng 1994; Tan & Ng 1994). In addition to the lectotype specimen of C. villosum, another Wroblewsky specimen originally from the Godeffroy Museum was found in the ZRC, although how it got there is not known, possibly from the time R. Serène was based in Singapore in the 1960 s. It is noteworthy that during that time, Serène was revising the IWP Sesarmidae with Soh Cheng Lan (e. g., see Serène & Soh 1970) and he had gathered material in Singapore for this work. The morphology of this Wroblewsky specimen, however, clearly matches what is here defined as C. suvaense and not C. villosum. Based on the specimen label, it has the same locality information as the lectotype of C. villosum. In addition to the very different morphology, the measurements of this specimen also do not match those listed in A. Milne-Edwards (1869) in his original description. It is unclear whether A. Milne-Edwards actually examined this specimen or if there is a mistake in the labels. There is also no mention of additional specimens of “ C. villosum ” in the eight sales catalogues of Godeffroy Museum that were published between 1864 and 1881 by curator J. D. E. Schmeltz other than that for the original specimen in A. Milne-Edwards (1896) or later papers by the author on the Godeffroy Museum collections (e. g. A. Mine-Edwards 1873 a). For the moment, we accept the record of C. suvaense as being also present in Samoa. Even though both C suvaense and C. villosum are found together in Samoa, it is important to note that currently, no specimens of C. villosum has been found in Fiji. Recent collections there only found C. suvaense. Records of “ C. suvaense ” from Singapore by Wee & Ng (1994) and Tan & Ng (1994) belong to C. nobile n. sp. instead. Although C. suvaense is superficially similar to C. villosum and C. nobile n. sp., they are relatively easy to distinguish, especially adult males. Clistocoeloma suvaense clearly differs from C. villosum s. str. in the presence of a distinct external orbital angle on the anterolateral margin of the carapace (Figs. 2 A, 3 A, 4 A) (the external orbital angle on the anterolateral carapace margin is not distinct and low in C. villosum; Fig. 1 A); the presence of a broad, rounded inner orbital angle (Figs. 3 C, 4 C) (the inner orbital angle is narrow and ovate in C. villosum; Fig. 1 C); possessing 25 – 26 granules on the dorsal surface of the dactylus of the adult male chela (Figs. 3 E, 5 D) (16 granules in C. villosum; Fig. 5 A); and the G 1 is straighter with a proportionately broader distal portion (Figs. 9 E – H, 10 A – H) (G 1 slightly curved with a narrower distal portion for C. villosum; Fig. 9 A – D). Fresh collections of C. suvaense from the type locality show that the species is not uncommon in Fiji, and all the recent specimens agree very well with the type material. Ecological notes. It was mentioned that the specimens were collected from “ a reef in Suva Harbor in 1933 ” (Edmondson 1951: 240). Fresh material was collected from the back mangrove at a higher elevation and found on muddy substrate under large loose rocks in Suva and Taveuni Island, Fiji. Specimens were found with layer of mud covering the entire crab.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFF3FFD3FF30FF29FDD1EE90.taxon	distribution	Distribution. Currently only known for certain from the type locality, Suva, as well as Taveuni Island, Fiji; the record from Samoa is uncertain.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	materials_examined	Type material. Holotype: male (15.3 × 12.7 mm) (ZRC 2022.0970), stn SW 7 (SS- 00221), pontoon at south lagoon, St. John’s Island, Singapore, 1 ° 12.92 ’ N, 103 ° 51.09 ’ E, coll. CMBS II Expedition, 20 May 2013. Paratypes: 1 female (18.7 × 15.2 mm) (ZRC 2022.0971), same locality and collection information as Holotype. — 3 males (16.2 × 13.8 mm, 15.9 × 14.2 mm, 12.6 × 11.0 mm), 1 female (13.2 × 11.2 mm) (ZRC 2002.0154), Kusu Island, Singapore, coll. C. D. Schubart, 15 April 2000. — 1 male (15.0 × 13.0 mm) (ZRC 2002.0155), Sungei Buloh, Singapore, coll. C. D. Schubart & N. Sivasothi, 16 August 1999. — 6 males (16.9 × 14.3 mm, 15.8 × 13.5 mm, 15.2 × 13.1 mm, 15.1 × 13.0 mm), 2 females (15.1 × 12.8 mm, 12.7 × 10.3 mm) (ZRC 2022.0972), Lazarus Island, Singapore, coll. B. Y. Lee et al., 30 September 2018. Other material examined. South Korea: 1 female (12.8 × 10.8 mm) (WS 900), Gosan, Jeju Island, coll. J. Jung, May 2003. — 1 female (14.5 × 12.1 mm) (WS 899), Gosan, Jeju Island, coll. J. Jung, May 2003. — 1 male (16.2 × 14.2 mm) (WS 898), Gosan, Jeju Island, coll. J. Jung, May 2003. Japan: 3 males (18.2 × 15.0 mm, 12.7 × 11.0 mm, 9.4 × 8.1 mm), 1 female (19.0 × 15.8 mm) (ZRC 2022.0990), Yagaji-jima, Okinawa, coll. J. J. Li, 18 July 2016. — 1 damaged female (11.9 × 10.1 mm) (ZRC 1999.0254), Nago City, Yagaji Island, coll. 23 May 1978. — 1 male (9.4 × 8.0 mm) (ZRC 2011.1037), Kumeijima, Okinawa, coll. T. Komai, 16 November 2009. — 1 female (10.3 × 8.8 mm) (ZRC 2011.1036), Ohara, Kumejima, 26 ° 20 ’ 57.8 ” N 126 ° 43 ’ 33.9 ” E, coll. Kumeijima 2009 Expedition, 18 November 2009. Taiwan: 1 ovigerous female (15.8 × 13.4 mm) (ZRC 2022.0991), Xiangjiaowan, coll. J. J. Li, 25 August 2014. — 1 ovigerous female (16.0 × 13.2 mm) (ZRC 2022.0992), Dintanzi, Hengchun Township, Pintung County, coll. Z. C. Ji, 3 September 2017. Hong Kong: 1 male (12.4 × 10.7 mm), 1 female (12.5 × 10.5 mm) (ZRC 2022.0993), To Kwa Peng, Sai Kung, coll. K. Wong, 9 May 2016. — 1 male (17.3 × 15.0 mm) (ZRC 2022.0994), Kak Po, Northeast Hong Kong, coll. C. Cheng & A. Quadros, 18 September 2017. Philippines: 1 male (17.4 × 14.9 mm), 1 female (14.9 × 12.7 mm) [photographed] (ZRC 2022.0973), stn M 52, Danao embayment, Panglao Island, coll. Panglao Marine Biodiversity Project, 30 June 2004. — 1 female (15.9 × 13.4 mm) (ZRC 2022.0974), Kawasan, Cebu, coll. H. - C. Liu, 25 November 2001. Vietnam: 1 male [photographed] (17.4 × 15.2 mm) (ZRC 2022.0975), stn CD-I- 08 (22), Bay Canh Island, 08 ° 40.125 ’ N 106 ° 40.933 ’ E, coll. 14 April 2010. — 1 female [photographed] (14.1 × 12.0 mm) (ZRC 2022.0976), stn CD-I- 08 (24), Bay Canh Island, 08 ° 40.125 ’ N 106 ° 40.933 ’ E, coll. 14 April 2010. — 1 male [photographed] (16.0 × 13.5 mm) (ZRC 2022.0977), stn CD-I- 08 (23), Bay Canh Island, 08 ° 40.125 ’ N 106 ° 40.933 ’ E, coll. 14 April 2010. — 8 males (16.5 × 14.2 mm, 14.0 × 12.0 mm, 7.6 × 6.3 mm, 6.1 × 5.1 mm), 17 females (16.2 × 13.1 mm, 14.9 × 12.6 mm, 7.6 × 6.5 mm, 5.0 × 4.3 mm) (ZRC 2022.0978), stn CD-I- 08, Bay Canh Island, 08 ° 40.125 ’ N 106 ° 40.933 ’ E, coll. 14 April 2010. Malaysia: 1 male (14.0 × 11.8 mm) (ZRC 2022.0979), Sungei Baharu mangrove, Pulau Tioman, coll. LSM 4263 students, 18 July 2014. — 1 male (11.6 × 9.8 mm) (ZRC 2016.0140), Telok Bakau, Pulau Tulai, Pulau Tioman, Pahang, coll. H. H. Tan & M. A. H. Chua, 16 July 2016. — 1 male (12.8 × 11.0 mm) (ZRC 2022.0980), Sungei Baharu mangrove, Pulau Tioman, coll. B. Y. Lee, 15 July 2014. — 2 males (12.5 × 11.0 mm, 8.2 × 7.8 m) (ZRC 2022.0981), Sungei Baharu mangrove, Pulau Tioman, coll. B. Y. Lee, 15 July 2014. — 1 female (17.6 × 14.6 mm) (ZRC 2000.1655), Pulau Manukan, Kota Kinabalu, Sabah, coll. C. D. Schubart, 22 June 2000. — 2 females (12.8 × 10.5 mm, 9.0 × 7.7 mm), 1 ovigerous female (12.5 × 10.1 mm), 1 juvenile female (5.5 × 4.9 mm) (ZRC 1969.10.13.3), Johore Straits, coll. C. L. Soh, 5 October 1969. — 3 males (12.8 × 11.0 mm, 9.8 × 8.8 mm, 9.7 × 8.6 mm), 4 females (15.8 × 13.8 mm, 13.4 × 11.3 mm, 9.3 × 8.0 mm, 7.7 × 6.6 mm) (ZRC 2022.0982), near Sungei Lengara, Langkawi Island, coll. A. D. Tran et al., 20 November 2006. — 2 males (12.5 × 11.0 mm, 9.6 × 8.3 mm) (ZRC 2022.0983), river mouth of Sungei Temurun, Langkawi, coll. T. Naruse, 20 November 2006. — 10 males (13.3 × 11.4 mm, 13.2 × 11.0 mm, 8.7 × 7.3 mm, 7.4 × 6.6 mm), 3 females (11.5 × 9.7 mm, 6.7 × 5.7 mm, 6.7 × 5.5 mm) (ZRC 1969.10.14.1 – 10), Johore Straits, coll. C. L. Soh, 12 October 1969. Indonesia: 1 male (11.2 × 9.7 mm), near NAD resort, Mawali Bay, Pulau Lembeh, Manado, Sulawesi, coll. H. H. Tan, December 2018.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	diagnosis	Diagnosis. Carapace slightly wider than long, almost square; postfrontal lobes weak, divided by weak longitudinal grooves; median pair slightly prominent, nearly equal in proportions. Inner orbital angle present, rounded, distinct, slight gap between inner orbital angle and frontal margin (Fig. 7 C). Anterolateral margin of carapace with distinct external orbital angle, second tooth blunt, weak or absent; posterolateral margin slightly convex (Figs. 2 B, C, 7 A). Chelipeds dorsal surface of dactylus of chela with between 20 – 31 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Fig. 5 E); presence of single longitudinal pectinated ridge with between 28 – 45 chitinous comb-like tubercles on dorsal surface of chela; row of 10 – 20 granules clustered behind pectinated ridge on chela; inner surface of palm granulated, vertical rows of 6 – 10 granules in adult male (Fig. 5 F). P 5 merus relatively short, wide, length approximately 0.36 – 0.43 times width (Fig. 6 E – K). G 1 slightly curved, distal region slightly wide; chitinous tip narrow, short; tip with dense tufts of setae, single row of plumose setae on exterior lateral margin; chitinous tip visible when denuded (Fig. 11 A – D). Female vulvae with central operculum, round, slightly protruded (Fig. 8 D).	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	description	Description. Carapace slightly wider than long, almost square; covered with dense coat of setae, including small tufts of setae resembling tubercles; carapace margin fringed with dense, short setae; carapace smooth when denuded. Postfrontal lobes weak, divided by weak longitudinal grooves; median pair slightly prominent, nearly equal in proportions. Inner orbital angle present, rounded, distinct, slight gap between inner orbital angle and frontal margin (Fig. 7 C). Anterolateral margin of carapace with distinct external orbital angle, second tooth blunt, weak or absent; posterolateral margin slightly convex (Figs. 2 B, C, 7 A). Antenna short. Antennules folding transversely. Third maxilliped with merus relatively rounded. Epistomial margin relatively narrow (Fig. 7 C). Chelipeds subequal in size; large, robust in male; outer surface of palm smooth when denuded; dorsal surface of carpus covered with small tufts of setae resembling tubercles, smooth when denuded.; dorsal surface of dactylus of chela with between 20 – 31 evenly spaced tubercles, proximal tubercles small, increasing in size medially, decreasing in size distally (Fig. 5 E); absent or weak granules in female and juveniles; presence of single longitudinal pectinated ridge with between 28 – 45 chitinous comb-like tubercles on dorsal surface of chela; row of 10 – 20 granules clustered behind pectinated ridge on chela; inner surface of palm granulated, vertical rows of 6 – 10 granules in adult male (Fig. 5 F). P 2 – P 5 covered with dense coat of setae, with small tufts of setae resembling tubercles, longer setae on dorsal and ventral margins except distal portion of dactylus (Figs. 2 B, C, 7 A); P 5 merus relatively short, wide, length approximately 0.36 – 0.43 times width (Fig. 6 E – K). Male thoracic sternum sparsely covered with short setae, smooth when denuded; sternites 1 and 2 fused, with suture between fused sternites 3 and 4; sternopleonal cavity extends nearly to edge of sternites 1 and 2. Male pleon wide and stout, long setae fringed pleon margin; somite 3 widest; somite 6 with curved edge; telson wide, dome-shaped (Fig. 7 B); male pleonal locking mechanism absent, without tubercle on sternite 5. G 1 slightly curved, distal region slightly wide; chitinous tip narrow, short; tip with dense tufts of setae, single row of plumose setae on exterior lateral margin; chitinous tip visible when denuded (Fig. 11 A – D). G 2 shorter than G 1, slightly curved, tip rounded. Female pleon rounded, relatively wider than long; telson dome-shaped (Fig. 8 C). Vulvae with central operculum, round, slightly protruded; sternal vulvar cover slightly raised above operculum (Fig. 8 D). Colouration. Chelipeds with fingers yellowish white and purple to purplish red palm (Fig. 2 B, C). In life, entire crab covered in a thin layer of mud.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	etymology	Etymology. The term, “ nobile ” alludes to the distinctive colour of the chela of the species; purple being a colour normally associated with royalty.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	discussion	Remarks. Clistocoeloma nobile n. sp. has a mix of diagnostic characters of C. villosum and C. suvaense. In the form of the carapace, C. nobile n. sp. has a weak external orbital angle on the anterolateral margin of carapace (Figs. 2 B, C, 7 A), and this is intermediate in form between C. villosum (which has no external orbital angle visible; Fig. 1 A) and C. suvaense (which has a distinct external orbital angle; Figs. 2 A, 3 A, 4 A). This character is very consistent in the large series of specimens of C. nobile n. sp. examined. With regards to the armature on the dorsal margin of the dactylus of the male chela, C. nobile n. sp. has 20 – 31 granules (Fig. 5 E), in contrast to only 16 granules present in C. villosum (Fig. 5 A). The number of granules in C. suvaense (22 – 27; Figs. 3 E, 5 C), however, overlaps with that of C. nobile n. sp. The G 1 of C. suvaense is also very similar to that of C. nobile n. sp., with the lateral view appearing stout with a distinct angle before chitinous tip in C. suvaense (Figs. 9 F, 10 B, F) while the lateral view appearing narrower with a weak angle visibile before the chitinous tip in C. nobile n. sp. (Fig. 11 B). The lateral view of the G 1 of C. villosum, on the other hand, appears narrow with no clear angle before chitinous tip (Fig 9 B). In addition, C. nobile n. sp. can also be separated from C. suvaense in having a rounded and slightly protruded vulvar cover (Fig. 8 D); which is ovate and less protruded vulvar cover in C. suvaense (Fig. 8 B). Females of C. villosum s. str. are not known. On the basis of these characters, it is clear that most of the records of “ C. villosum ” from the IWP, including Singapore, belong to C. nobile n. sp. instead. For the record by Tesch (1917: 208 – 210, pl. 17 fig. 2), his description and figures of the female specimen match C. nobile n. sp.. Tesch (1917) had noted that the New Guinea specimens has a distinct external orbital angle, in contrast to the type of C. villosum described by De Man (1987: 644) which has an indistinct one. The older records of “ Cleistocoeloma suvaense ” from Singapore by Tan & Ng (1994) and Wee & Ng (1994), are based on specimen records in the ZRC, are here referred to C. nobile n. sp. instead. A number of records of “ C. villosum ” from the IWP, however, are in doubt as we have neither specimens from these areas nor good descriptions and / or figures on which to base our decisions (see later). Ecological notes. Clistocoeloma nobile n. sp. is not a mangal species, although it has been found in habitats near mangroves. Most of the Singapore specimens were found in muddy substrates amongst the rocky intertidal areas in the supralittoral zone, typically found under large rocks with muddy substrate. For the Japanese specimens (as C. villosum), it was observed by Komai et al. (2004) that it can be found underneath rocks or fallen leaves within the landward side of the mangrove, while Yuhara et al. (2017) noted that this species was found underneath gravels and cobble stones around the edges of mangrove forests. For the Korean material, Lee et al. (2010) noted that the species occurred in “ slightly moist soil under fallen leaves ”.	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
C4481C7DFFFEFFC5FF30FF29FBF7EB2C.taxon	distribution	Distribution. Singapore (type locality), Sumatra (De Man 1897, 1898), Caroline Islands (Rathbun 1907), New Guinea (Tesch 1917), the Philippines (McNeill 1968), Taiwan (Li 2015; Li et al. 2019), Japan (Komai et al. 2004; Yuhara et al. 2017; Takakura & Komai 2019), and South Korea (Lee et al. 2010).	en	Ng, Bee Yan Lee Ngan Kee, Ng, Peter K. L. (2023): On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata). Zootaxa 5318 (2): 217-236, DOI: 10.11646/zootaxa.5318.2.3, URL: http://dx.doi.org/10.11646/zootaxa.5318.2.3
