[Crustacea • 2018] Parasesarma peninsulare • Morphological and Phylogenetic Evidence for A New Species of Parasesarma De Man, 1895 (Decapoda: Brachyura: Sesarmidae) from the Malay Peninsula, previously referred to as Parasesarma indiarum (Tweedie, 1940)

 Parasesarma peninsulare 

Shahdadi, Ng & Schubart, 2018

RAFFLES BULLETIN OF ZOOLOGY. 66; 

Abstract 

A colourful crab currently referred to as Parasesarma indiarum (Tweedie, 1940) is a relatively common species in Southeast Asian mangroves and has been recorded from Singapore, Malaysia, and Indonesia. The present study compares the material from Singapore and Peninsular Malaysia to the type specimens from Ambon, and recognises two species based on their morphology and genetic distances. The structure of the chelar dactylar tubercles and molecular data support the distinction of specimens originating from Peninsular Malaysia and Singapore from those of Ambon corresponding to P. indiarum sensu stricto. We here describe them as a separate species, Parasesarma peninsulare new species, and compare it with allied congeners. 

Key words. taxonomy, mangrove crab, pseudocryptic species, new species, Singapore, Peninsular Malaysia, Indonesia

SYSTEMATICS 

Family Sesarmidae Dana, 1851 

Genus Parasesarma De Man, 1895, 

sensu Shahdadi & Schubart, 2017 

Type species. Cancer quadratus Fabricius, 1798, 

subsequent designation by Rathbun (1918). 

Fig. 10.  Parasesarma peninsulare new species,
holotype, male (25.5 × 22.2 mm) (ZRC 2017.1075). A, dorsal habitus; B, ventral habitus.

 Parasesarma peninsulare new species

Sesarma (Chiromantes) bidens indica: Tweedie, 1936: 66. (not Sesarma bidens var. indica De Man, 1902) 

Sesarma bidens indiarum: Tweedie, 1940: 93 (part) (not Sesarma bidens indiarum Tweedie, 1940). 

Chiromantes indiarum: Tan & Ng, 1994: 82 (list).

Perisesarma indiarum: Boon et al., 2008; Huang et al., 2008; Boon et al., 2009; Ng et al., 2008: 225, fig. 162 (not Sesarma bidens indiarum Tweedie, 1940).

Etymology. This species is named after its known area of distribution, the Malay Peninsula. 

Fig. 14. Parasesarma peninsulare new species, colour in life.
 A–D, male; E–F, female; specimens not collected.
 A, E, dorsal habitus; B, F, ventral habitus; C, D, G, front view; H, left chela, outer view.

Distribution. Based on present material, so far known from both coasts of the Malay Peninsula, including the western coast to Thap Lamu, eastern side Chumphon (both Thailand), southward to Singapore and Batam Island (Riau Archipelago, Indonesia).

Habitat. In its distribution range, P. peninsulare new species is a relatively common species in mangroves swamps and can sometimes be found in good numbers, occasionally in partial sympatry with P. eumolpe, on muddy substrates. They are active burrowers, with burrow mouths often found within the aerial root systems of mangrove tree (Huang et al., 2008; Boon et al., 2009).

Adnan Shahdadi, Peter K. L. Ng and Christoph D. Schubart. 2019. Morphological and Phylogenetic Evidence for A New Species of Parasesarma De Man, 1895 (Crustacea: Decapoda: Brachyura: Sesarmidae) from the Malay Peninsula, previously referred to as Parasesarma indiarum (Tweedie, 1940). RAFFLES BULLETIN OF ZOOLOGY. 66; 739–762.   lkcnhm.nus.edu.sg/app/uploads/2018/01/66rbz739-762.pdf