Eurycarcinus bengalensis Deb, 1999

Trivedi, Jigneshkumar, Mitra, Santanu, Patel, Pooja, Maheta, Niketa, Patel, Krupal & Ng, Peter K. L., 2021, On the Indian species of Eurycarcinus A. Milne-Edwards, 1867, Heteropanope Stimpson, 1858, and Pilumnopeus A. Milne-Edwards, 1867 (Decapoda: Brachyura: Pilumnidae), Nauplius (e 2021004) 29, pp. 1-18 : 5-9

publication ID	https://doi.org/ 10.1590/2358-2936e2021004
publication LSID	lsid:zoobank.org:pub:51870B2A-C089-4A53-9EA2-584160AADEEE
DOI	https://doi.org/10.5281/zenodo.10910315
persistent identifier	https://treatment.plazi.org/id/105F0E68-FF9D-072C-FC24-F5B3D9B2FB2B
treatment provided by	Felipe
scientific name	Eurycarcinus bengalensis Deb, 1999
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Eurycarcinus bengalensis Deb, 1999 View in CoL

( Figs. 3 View Figure 3 , 4 View Figure 4 , 9G–I View Figure 9 )

Eurycarcinus bengalensis Deb, 1999: 376 View in CoL (part), fig. 2.

Heteropanope bengalensis View in CoL — Ng et al., 2018: 474; Trivedi et al., 2018: 59.

Material examined. Holotype, male ( CW 25.1 mm; CL 16.9 mm), ZSI-C3349/2, Chamta Block, Sunderbans Tiger Reserve , West Bengal State, India, coll. S. Bhuinya. Paratypes, 2 males ( CW 11.5 mm; CL 7.8 mm, CW 11.7 mm; CL 8.6 mm) , data as per holotype.

Remarks. Deb (1999) described E. bengalensis on the basis of a holotype and an unspecified number of specimens collected from Sundarbans Tiger Reserve, West Bengal state, India. Ng et al. (2018) provisionally transferred this species to Heteropanope on the basis of the figure and description of the type specimen given in Deb (1999). In the present study, the type specimens of the species were examined and identified as Eurycarcinus because the thoracic sternite 8 of the specimen remains exposed when the male pleon is closed ( Fig. 3E View Figure 3 ) and pleonal somite 3 is relatively wider, with the lateral margin projecting ( Fig. 3C View Figure 3 ), which are characteristics of Eurycarcinu s.

The type series of E. bengalensis is mixed. Of the five specimens, the two paratype males agree well with the holotype male in most aspects and are clearly conspecific.The two ovigerous females (CW 13.9 mm, CL 10.4 mm; CW 21.3 mm, CL 15.3 mm), however, belong to E. integrifrons instead. The carapace shape and features ( Fig. 4 View Figure 4 ) are clearly of this species.

Eurycarcinus bengalensis s. str. is similar to E. integrifrons in the following characters: the carapace is not prominently swollen and high in frontal view ( Figs.2A View Figure 2 , 3A View Figure 3 , 4A View Figure 4 ), the frontal margin is weakly bilobed ( Figs. 2B View Figure 2 , 3B View Figure 3 , 4B View Figure 4 ), there are distinct clumps of short setae between the first to third anterolateral teeth ( Figs. 2A View Figure 2 , 3A View Figure 3 , 4A View Figure 4 ), the supraorbital margin is smooth without granules, the sub-orbital and pterygostomial regions are smooth and glabrous with dense setae only along the sutures ( Figs. 2B View Figure 2 , 3B View Figure 3 , 4B View Figure 4 ), and the posterior margin of the epistome has the median lobe truncate, protruding anteriorly and separated from lateral margin by distinct rounded angle ( Figs. 2B View Figure 2 , 3B View Figure 3 , 4B View Figure 4 ). Eurycarcinus bengalensis , however, differs from E. integrifrons in several characters that cannot be explained by variation: the carapace of E. bengalensis is proportionately wider ( Figs. 3A View Figure 3 , 4A View Figure 4 ) (more quadrate in E. integrifrons ; Fig. 2A View Figure 2 ); the anterolateral teeth are lobiform and wide, separated from each other by a fissure ( Figs. 3A View Figure 3 , 4A View Figure 4 ) (more narrow dentiform anterolateral margin with the teeth separated by a U-shaped hiatus in E. integrifrons ; Fig 2A View Figure 2 ); the male chela is proportionately shorter ( Fig. 3D View Figure 3 ) (more elongate in E. integrifrons ; Fig 2D View Figure 2 ); male pleonal somite 6 is distinctly trapezoidal in shape ( Fig. 3C View Figure 3 ) (less so in E. integrifrons ; Fig. 2C View Figure 2 ); male pleonal somites 1–3 are proportionately less broad ( Fig. 3E View Figure 3 ) (proportionately wider in E. integrifrons ; Fig. 2E View Figure 2 ); and the distal part of the G1 is relatively shorter with the tip gently upcurved ( Fig. 9G, H View Figure 9 ) (G1 distal part relatively longer with the tip almost straight or gently curved downwards in E. integrifrons ; Fig. 9D, E View Figure 9 ).

The relative width of the carapace and proportions of male pleonal somites 1–3 of E. bengalensis ( Figs. 3A View Figure 3 , 4A View Figure 4 , 3E View Figure 3 ) are actually closer to the condition in E. orientalis ( Figs. 1A, E View Figure 1 ) but the other characters (notably carapace shape, anterolateral armature, posterior margin of the epistome, male pleon shape and G1) do not match.

The characters possessed by E. bengalensis are interesting. While its carapace closely resembles species of Heteropanope as indicated by Ng et al. (2018), the male sternal and pleonal characters are those of Eurycarcinus . It is possible that some, if not all the records of “ Eurycarcinus natalensis ” and “ Eurycarcinus orientalis ” from the eastern Indian Ocean (e.g., Dev Roy, 2008; Rath and Dev Roy, 2009; see under E. orientalis ) actually belong to E. bengalensis instead. The material will need to be examined.