Pseudosesarma brehieri Ng 2018
Creators: name: Schubart, Christoph D.
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Sesarmidae
Pseudosesarma
Pseudosesarma brehieri

description: Pseudosesarma brehieri Ng, 2018
(Figs. 22G, 25F, 27G, 30G, 37A–I, 44 E)
Pseudosesarma brehieri Ng, 2018: 191, figs. 4–6, 7D–I; Trivedi et al., 2020: 4, fig. 3.
Material examined. Holotype: male (17.4 × 15.7 mm) (ZRC 2016.0593), Nathack Gu (Two Level Cave), near Saddan Sin Gu, Mawlamyine (Moulmein), Mon State, 16°31′33.5″N 097°42′48.8″E, Myanmar, coll. F. Bréhier et al., 26 November 2016. Paratype: 1 female (14.9 × 13.4 mm) (ZRC 2016.0594), same data as holotype. Others: INDIA – 5 males (11.9 × 10.4 mm, 12.4 × 10.9 mm, 13.6 × 11.7 mm, 14.5 × 13.0 mm, 15.0 × 13.6 mm) (ZRC 2013.0209), river bank, Bhagirath, Nabadiwip, Nadia, West Bengal, coll. Z. Jaafar et al., 26 December 2004.
Diagnosis. Carapace quadrate, slightly wider than long, width to length ratio 1.1; frontal margin wide, median concavity separating lobes relatively shallow; external orbital tooth short, not reaching to level of front, lateral margin with 2 epibranchial teeth; posterolateral margins subparallel; chela short, stout, fingers shorter than palm, outer surface of chela covered with numerous granules, ventral margin of palm almost straight or gently convex; suture between male thoracic sternites 3 and 4 distinct; male pleon triangular, somite 6 wide; male sternopleonal cavity with press-button of pleonal locking mechanism on sternite 5; G1 stout, distal part prominently dilated forming bulbous structure, chitinous tip short, broad, truncate, fan-like.
Colour. Not known.
Remarks. The species was described and figured in detail by Ng (2018). Pseudosesarma brehieri most closely resembles P. crassimanum but can easily be separated by the ventral margin of its adult male chela being almost straight (Fig. 27G) and the distal half of the G1 being proportionately more dilated with the chitinous distal part very wide and fan-like (Fig. 37B–D, F–I) (versus ventral margin of adult male chela gently concave, and the G1 distal part less dilated with the chitinous distal part narrow and beak-like in P. crassimanum; Figs. 27D, 35 B–F, H–L, O–R).
Biology. Ng (2018: 193, 195) observed that the type specimens of P. brehieri were found in a small upper chamber of a cave at the foot of the hill not far from Saddan Sin Gu in southern Myanmar. The water in the cave was completely fresh. The site is not far from the sea and the species is clearly not an obligate cave species with well developed eyes and normal colouration. Trivedi et al. (2020: 4) recorded the species from India, noting that the material was “collected from [the] muddy shore of Hooghly River at Barrackpore city of West Bengal state which is considered as upper reaches of Hooghly-Matla estuary, where tidal effects usually occur with a low salinity (0.5 to 4 ppm) of interstitial waters”. The present specimens from India were collected from the side of a riverbank in an estuarine habitat in West Bengal, India.
Distribution. The species was described from Myanmar and we now also have specimens from Bengal in eastern India (ZRC 2013.0209).
description: Published as part of Schubart, Christoph D. & Ng, Peter K. L., 2020, Revision of the intertidal and semiterrestrial crab genera Chiromantes Gistel, 1848, and Pseudosesarma Serène & Soh, 1970 (Crustacea: Brachyura: Sesarmidae), using morphology and molecular phylogenetics, with the establishment of nine new genera and two new species, pp. 891-994 in Raffles Bulletin of Zoology 68 on pages 950-952, DOI: 10.26107/RBZ-2020-0097, http://zenodo.org/record/5351295