Metaplax elegans De Man, 1888

Shih, Hsi-Te, Hsu, Jhih-Wei, Wong, Kingsley J. H. & Ng, Ngan Kee, 2019, Review of the mudflat varunid crab genus Metaplax (Crustacea, Brachyura, Varunidae) from East Asia and northern Vietnam, ZooKeys 877, pp. 1-29 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.877.38300
persistent identifier	https://treatment.plazi.org/id/AF9022BC-3B84-59F5-86CE-B87FC3E1DB85
treatment provided by	ZooKeys by Pensoft (2019-10-02 14:22:53, last updated 2025-04-04 05:42:29)
scientific name	Metaplax elegans De Man, 1888
status

Treatment

Metaplax elegans De Man, 1888 View in CoL Figures 2 A–C View Figure 2 , 3 View Figure 3 , 7 A–D View Figure 7

Metaplax elegans De Man, 1888: 164, pl. 11(4-6) (type locality: Mergui, Myanmar); Alcock 1900: 434 (East India: Godavari Delta; Myanmar: Mergui); Gordon 1931: 528 (Hong Kong); Rathbun 1931: 100 (China: Fujian; Guangdong); Tweedie 1936: 69 (Malaysia: Selangor; Singapore); Shen 1940a: 74, 95 (China: Zhejiang; Fujian); Shen 1940b: 236 (Hong Kong); Tweedie 1950: 353 (Malaysia: Labuan; Kuching); Macnae 1963: 104, 180 (list); Dai et al. 1986: 509, fig. 289 (1-2), pl. 72(5) (China: Guangdong); Fukui et al. 1989: 230, fig. 25 (W Taiwan); Dai and Yang 1991: 557, fig. 289 (1-2), pl. 72(5) (China: Guangdong); J.-T. Shih et al. 1991: 126 (Taiwan: New Taipei City); Davie 1992: 352, pl. 2B (Hong Kong); Choy and Booth 1994: 243 (Brunei); Huang 1994: 598 (list; China); Tan and Ng 1994: 82 (Singapore; Malaysia); Kuo 1995: 31, 82, 97, 191, 4 unnumbered figs (W Taiwan); Wang and Liu 1996a: 128, figs 171-172 (W Taiwan); Wang and Liu 1996b: 103-104, 2 unnumbered figs (W Taiwan); Fransen et al. 1997: 125 (syntype; Mergui, Myanmar); Ho and Hung 1997: 108-109, 1 unnumbered fig.; Kosuge et al. 1997: 182 (Vietnam: Haiphong); Jeng et al. 1998: 68, 3 unnumbered figs (Taiwan: Taichung); Wang and Liu 1998a: 128, figs 171-172 (W Taiwan); Wang and Liu 1998b: 142, 2 unnumbered figs (W Taiwan); Lee and Leung 1999: 68, pl. 11 (Hong Kong); Ng and Sivasothi 1999: 73, 2 unnumbered figs (Singapore); Jeng and Wang 2000: 38, 2 unnumbered figs (Taiwan: Taichung); Lee and Tung 2000: 70 (list); Dev Roy and Bhadra 2011: 36 (list; E India); Lee 2001: 114, 3 unnumbered figs (W Taiwan); Ng et al. 2001: 45 (list; Taiwan); Kitaura et al. 2002: 684 (Vietnam: Haiphong); Ng and Davie 2002: 379 (Thailand: Phuket); Wang and Liu 2003: 128, figs 171-172 (W Taiwan); Naiyanetr 2007: 112 (list: Gulf of Thailand); Dev Roy 2008: 135 (list; India); Huang 2008: 668 (list; China); Ng et al. 2008: 226 (list); Yang et al. 2008: 803 (list; East and South China seas); Rath and Dev Roy 2008: 72, pl. 4(5) (NE India); Liu and Wang 2010: 72, 3 unnumbered figs (W Taiwan); Lee et al. 2013: 108, 2 unnumbered figs (Taiwan: Tainan); Ng et al. 2017: 110 (list; Taiwan).

Materials examined.

Taiwan: 8 ♂♂ (6.1-14.0 mm), 4 ♀♀ (8.0-13.2 mm) (NCHUZOOL 15479), Danshuei River mangroves, New Taipei City, coll. P.-Y. Hsu and J.-W. Hsu, 24 Mar. 2017; 4 ♂♂ (11.8-15.9 mm), 4 ♀♀ (14.1-15.3 mm) (NCHUZOOL 15480), Jhuwei, New Taipei City, 4 Oct. 1995; 1 ♂ (12.1 mm) (NCHUZOOL 15481), Sinfeng, Hsinchu, 15 Jan. 2014; 2 ♂♂ (8.4-10.5 mm), 5 ♀♀ (6.3-12.1 mm) (NCHUZOOL 15482), Siangshan, Hsinchu, 11 Aug. 2008; 1 ♂ (13.2 mm), 5 ♀♀ (8.7-9.7 mm) (NCHUZOOL 15483), Siangshan, Hsinchu, 13 Mar. 2008; 4 ♂♂ (10.1-11.3 mm), 1 ♀ (11.7 mm) (NCHUZOOL 15484), Haishangu, Hsinchu, 27 Aug. 2013; 1 ♂ (10.8 mm), 3 ♀♀ (8.8-11.6 mm) (NCHUZOOL 15485), Wufu Bridge, Miaoli, 2 Dec. 2015; 4 ♂♂ (12.0-15.1 mm) (NCHUZOOL 15486), Fangyuan, Changhua, 2014; 4 ♂♂ (10.0-12.2 mm), 6 ♀♀ (8.1-12.1 mm) (NCHUZOOL 15487), Yuliao R. estuary, Changhua, coll. J.-W. Hsu et al., 16 Jan. 2017; 4 ♂♂ (5.3-10.6 mm), 3 ♀♀ (10.2-12.9 mm) (NCHUZOOL 15488), area between Yunlin and Chiayi, coll. K.-C. Li and C.-T. Wang, 25 Aug. 2003; 1 ♂ (12.7 mm) (NCHUZOOL 15496), Dongshih, Chiayi County, coll. P.-Y. Hsu, 24 Jan. 2017; 4 ♂♂ (11.5-13.1 mm), 3 ♀♀ (6.7-10.7 mm) (NCHUZOOL 15489), Cihhu, Kinmen, coll. H.-T. Shih and P.-Y. Hsu, 29 June 2018. China: 3 ♀♀ (14.0-16.8 mm) (NCHUZOOL 15495), Dongzhai Harbor, Hainan, 23 June 2004; 3 ♀♀ (13.9-16.6 mm) (NCHUZOOL 15457), Dongzhai Harbor, Hainan, 23 June 2004. Vietnam: Ho Chi Minh: 8 ♂♂ (5.8-16.5 mm), 9 ♀♀ (6.5-13.7 mm) (NCHUZOOL 15490), Rung Sac, Long Hoa, 12 Oct. 2017; 1 ♂ (18.2 mm), 1 ♀ (12.7 mm) (NCHUZOOL 15491), TT. Can Thanh mangroves, Can Gio, 13 Oct. 2017; 5 ♂♂ (16.0-17.6 mm) (NCHUZOOL 15499), TT. Can Thanh mangroves, Can Gio, 13 Oct. 2017. Malaysia: 7 ♂♂ (7.7-12.6 mm), 14 ♀♀ (8.9-12.0 mm) (NCHUZOOL 15492), Mersing, Johor, 19 July 2010. Singapore: 1 specimen (not examined, only for DNA study; ZRC 1997.683), Sungei Buloh, 1996; 2 ♂♂ (9.4-11.0 mm), 1 ♀ (6.4 mm) (NCHUZOOL 15493), Lim Chu Kang, 4 Mar. 2012. Thailand: 1 ♀ (10.71 mm) (NCHUZOOL 15494), Ranong mangroves, 27 May 2012.

Diagnosis.

Carapace ( Figs 2A View Figure 2 , 3A, F View Figure 3 ) trapezoidal, 1.45 times as broad as long (N = 127, SD = 0.06), longitudinally convex, broadest between lateral teeth 2 (exorbital angle included), surface sparsely but regularly furnished with short, stiff setae; front broad, divided into two broad lobes, medially concave; lateral margins markedly converging posteriorly, interrupted by four notches, delineating five teeth (including exorbital angle), exorbital angle most distinct, posterior two indistinct; posterolateral facet faintly defined, decorated by two oblique granular ridges. Infraorbital ridge ( Figs 2B View Figure 2 , 3C View Figure 3 ) distinctly sexual dimorphic, males with 47-61 tubercles, medial seven closely set, almost fusing, lateral ca. 20 tubercles slightly vertically elongated; females with 33-42 isomorphic tubercles. Chelipeds ( Figs 2C View Figure 2 , 3D View Figure 3 ) symmetrical, in males more elongated and robust, palm 2.2 times as long as broad, length of palm approximately 1.8 times longer than dactyl (N = 20), pollex of chela with low sinuous tooth along cutting margin, dactylus with distinct triangular molar. Ambulatory legs elongated, meri broad, merus of P4 distally armed with several short spines on anterior margin; anterior margins of all ambulatory legs fringed with setal patches. G1 ( Fig. 7 A–D View Figure 7 ) long, slender, distal process triangular, distinctly curved outward.

Distribution.

The Bay of Bengal, Southeast and East Asia: China (Zhejiang; Fujian; Guangdong; Hainan), western Taiwan (including Kinmen), Vietnam, Malaysia (Selangor; Sarawak; Labuan), Singapore, Brunei, Thailand, Myanmar (Mergui), and eastern India (Tamil Nadu, Godavari Delta) ( Fig. 1 View Figure 1 ).

Habitat.

At Wazihwei Wetland, estuaries of Danshuei River, northwestern Taiwan, this species is found along shores with substantial freshwater influence, on banks with substrates plastic-muddy, somewhat distant from mangrove stands.

Remarks.

According to previous descriptions (De Man 1888, Dai et al. 1986, Dai and Yang 1991), the infraorbital ridges of M. elegans bear 50-60 tubercles in males and 35-40 tubercles in females. In the present study of 21 males and 19 females, CW ranging from 7.7 to 15.9 mm, and the range of variation is slightly wider than previously reported, being 47-61 in males and 33-42 isomorphic tubercles in females (Table 2 View Table , Fig. 8 View Figure 8 ).

References

Alcock, A, 1900. Materials for a carcinological fauna of India. No. 6. The Brachyura Catometopa, or Grapsoidea. Journal of the Asiatic Society of Bengal 69: 279 - 456

Choy, SC, Booth, WE, 1994. Prolonged inundation and ecological changes in an Avicennia mangrove: implications for conservation and management. Hydrobiologia 285: 237 - 247

Dai, AY, Yang, SL, Song, YZ, Chen, GX, 1986. Crabs of the China seas. China Ocean Press, Beijing

Dai, AY, Yang, SL, 1991. Crabs of the China Seas. China Ocean Press, Beijing

Dev Roy, MK, 2008. An annotated checklist of mangrove and coral reef inhabiting brachyuran crabs of India. Records of the Zoological Survey of India, Occasional Paper 289: 1 - 212

Fransen, CHJM, Holthuis, LB, Adema, JPHM, 1997. Type-catalogue of the decapod Crustacea in the collections of the Nationaal Natuurhistorisch Museum, with appendices of pre-1900 collectors and material. Zoologische Verhandelingen, Leiden 311: 1 - 344

Fukui, Y, Wada, K, Wang, CH, 1989. Ocypodidae, Mictyridae and Grapsidae (Crustacea: Brachyura) from some coasts of Taiwan. Journal of Taiwan Museum 42: 225 - 238

Gordon, I, 1931. Brachyura from the coasts of China. Journal of the Linnean Society (Zoology) 38: 525 - 558

Ho, PH, Hung, MS, 1997. Seashore Crabs of Hsin-Chu City. Hsinchu City Government, Hsinchu City

Huang, ZG, 1994. Marine Species and their Distributions in China's seas. China Ocean Press, Beijing

Huang, ZG, 2008. Marine Species and their Distributions in China. China Ocean Press, Beijing

Jeng, CH, Ling, HJ, Wang, MF, Jan, CP, 1998. Common Seashore Crabs of Taichung. Yungan Primary School, Taichung, Taiwan

Jeng, CH, Wang, MF, 2000. A Field Guide of Crabs. Taichung Nature Research Society, Taichung

Kitaura, J, Wada, K, Nishida, M, 2002. . https://doi.org/10.1651/0278-0372(2002)022[0682:MPOGAO]2.0.CO;2

Kuo, CY, 1995. Natural Trip of Taiwanese Mangroves. Bigtrees Co., Taipei

Lee, JH, Tung, SC, 2000. Crabs of Tainan County coast. Tainan County Government and Kung San Institute of Technology, Tainan

Lee, JH, 2001. A Field Guide to Crabs in Taiwan. Bigtrees Co., Taipei

Lee, JH, Chiu, YW, Wu, TT, Tseng, LK, Huang, YC, 2013. A Field Guide to the Shrimps, Crabs and Shells of Taijiang National Park. Taijiang National Park, Tainan City

Liu, HC, Wang, CH, 2010. Taiwan Coastal Wetland Crabs. Wild Bird Society of Taipei, Taipei

Macnae, W, 1963. A general account of the fauna and flora of mangrove swamps and forests in the Indo-West-Pacific Region. Advances in Marine Biology 6: 73 - 270

Man, JGD, 1888. Report on the podophthalmous Crustacea of the Mergui Archipelago, collected for the Trustees of the Indian Museum, Calcutta, by Dr. John Anderson, F.R.S., Superintendent of the Museum. Journal of the Linnean Society (Zoology) 22: 1 - 311

Naiyanetr, P, 2007. Checklist of Crustacean Fauna in Thailand (Decapoda, Stomatopoda, Anostraca, Myodocopa and Isopoda). Office of Natural Resources and Environmental Policy and Planning, Bangkok

Ng, PKL, Sivasothi, N, 1999. A Guide to the Mangroves of Singapore - Volume 1: The ecosystem and plant diversity. Singapore Science Centre, Singapore

Ng, PKL, Wang, CH, Ho, PH, Shih, HT, 2001. An annotated checklist of brachyuran crabs from Taiwan (Crustacea: Decapoda). National Taiwan Museum Special Publication Series 11: 1 - 86

Ng, PKL, Davie, PJF, 2002. A checklist of the brachyuran crabs of Phuket and western Thailand. Phuket Marine Biological Center Special Publication 23: 369 - 384

Ng, PKL, Guinot, D, Davie, PJF, 2008. Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology, Supplement 17: 1 - 296

Ng, PKL, Shih, HT, Ho, PH, Wang, CH, 2017. An updated annotated checklist of brachyuran crabs from Taiwan (Crustacea: Decapoda). Journal of the National Taiwan Museum 70: 1 - 208

Rathbun, MJ, 1931. New and rare Chinese crabs. Lingnan Science Journal 8: 75 - 125

Shen, CJ, 1940a. On the collections of crabs of South China. Bulletin of the Fan Memorial Institute of Biology (Zoology) 10: 69 - 104

Shen, CJ, 1940b. The brachyuran fauna of Hong Kong. Journal of the Hong Kong Fisheries Research Station 1: 211 - 242

Shih, JT, Lue, KY, Wang, CH, 1991. Crab fauna and the activities of ten crab species in Tanshui mangrove swamp of Taiwan. Annual of Taiwan Museum 34: 121 - 140

Tan, CGS, Ng, PKL, 1994. An annotated checklist of mangrove brachyuran crabs from Malaysia and Singapore. Hydrobiologia 285: 75 - 84

Tweedie, MWF, 1936. On the crabs of the family Grapsidae in the collection of the Raffles Museum. Bulletin of the Raffles Museum, Singapore 12: 44 - 70

Tweedie, MWF, 1950. Grapsoid crabs from Labuan and Sarawak. Sarawak Museum Journal 5: 338 - 369

Wang, CH, Liu, HC, 1996a. Common Seashore Crabs of Taiwan. Taiwan Museum, Taipei

Wang, CH, Liu, HC, 1996b. Estuarine Crabs of Taiwan. Wild Bird Society of Kaohsiung, Kaohsiung

Wang, CH, Liu, HC, 1998a. Common Seashore Crabs of Taiwan (2nd edn). Taiwan Museum, Taipei

Wang, CH, Liu, HC, 2003. Common Seashore Crabs of Taiwan (3rd edn). Taiwan Museum, Taipei

Figures

Figure 1. Collection sites (solid symbols) for species of the genus Metaplax used in this study: green rhombus for M. elegans; red circles for M. longipes; blue triangles for M. sheni; and purple squares for M. tredecim. Empty symbols mean the additional records from references (see synonym lists for each species).

Figure 2. Metaplax elegans De Man, 1888 (A-C NCHUZOOL 15496, male, 12.7 mm), M. longipes Stimpson, 1858 (D-F ZRC 2019.0581, male, 14.9 mm), M. sheni Gordon, 1930 (G-I NCHUZOOL 15466, male, 9.9 mm), and M. tredecim Tweedie, 1950 (J-L paratype, ZRC 1964.7.14.4 - 18, 16.2 mm). A, D, G, J, A carapace B, E, H, K left infraorbital ridge C, F, I, L outer view of right cheliped. Scale bars: 1.0 mm.

Figure 3. Metaplax elegans De Man, 1888. A Dorsal view B ventral view C left infraorbital ridge D right cheliped A-D male (CW 12.7 mm; NCHUZOOL 15496; Dongshih, Chiayi County, Taiwan) E, F live coloration E photo taken in Gaomei, Taichung, Taiwan (specimen not collected) F-G male (CW 13.1 mm; NCHUZOOL 15489; Kinmen, Taiwan) G the typical habitat (Gaomei, Taichung, Taiwan). Scale bars: 2.0 mm.

Figure 7. Metaplax elegans De Man, 1888 (A-D NCHUZOOL 15496, male, 12.7 mm), right G 1; M. longipes Stimpson, 1858 (E-H ZRC 2019.0581, male, 14.9 mm), right G 1; M. sheni Gordon, 1930 (I-L NCHUZOOL 15466, male, 9.9 mm), right G 1; and M. tredecim Tweedie, 1950 (M-P paratype, ZRC 1964.7.14.4 - 18, 16.2 mm), left G 1. Scale bars: 0.5 mm (A-H, M-P); 0.2 mm (I-L).

Figure 8. The number of infraorbital tubercles and lobes plotted as a function of carapace width (CW) of Metaplax elegans De Man, 1888, M. longipes Stimpson, 1858, M. sheni Gordon, 1930, and M. tredecim Tweedie, 1950.