Pseudosesarma anteactum Ng & Schubart, 2017

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, Raffles Bulletin of Zoology 68, pp. 891-994 : 948-949

Pseudosesarma anteactum Ng & Schubart, 2017

( Figs. 22E , 25D , 27E , 30F , 36A–G , 44 D)

Sesarma edwardsii – Alcock, 1900: 416 (part). [not Sesarma edwardsii De Man, 1887 ]

Sesarma (Sesarma) edwardsi crassimana – Ingle & Fernando, 1963: 101, figs. 1, 2a, b. [not Sesarma edwardsii var. crassimana De Man, 1887 ]

Pseudosesarma crassimanum – Bouillon et al., 2004: 84; Dahdouh-Guebas et al., 2011: 192. [not Sesarma edwardsii var. crassimana De Man, 1887 ]

Pseudosesarma anteactum Ng & Schubart, 2017: 664 , figs. 14–17.

Material examined. Holotype male (16.7 × 14.7 mm) ( ZRC 2016.0602 ), Colombo, Sri Lanka, coll. R. Serène, 12 October 1972. Paratypes: 3 males (21.2 × 19.7 mm, 17.2 × 15.9 mm, 14.1 × 12.2 mm), 2 females (17.5 × 15.4 mm, 15.7 × 14.2 mm) ( ZRC 2016.0603 ), same data as holotype .

Diagnosis. Carapace transversely rectangular; frontal margin relatively wide, median concavity separating lobes distinct; epibranchial tooth distinct, separated from rest of margin by deep notch; posterolateral margins subparallel; outer surface of chela gently convex, covered with closely packed rounded granules, ventral margin of palm gently convex, lined with rounded granules, not denticulate, fingers relatively short; suture between male thoracic sternites 3 and 4 distinct; male pleon broadly triangular; male sternopleonal cavity with press-button of pleonal locking mechanism on sternite 5; distal half of G1 gently swollen, wider than proximal part, median part appears gently constricted, chitinous part forming relatively wide beak-like structure. In life, chela red, not extending beyond base of fingers.

Colour. Ingle & Fernando (1963: 102) described the palm of the cheliped as red but with the colour not extending beyond the base of the fingers.

Remarks. The species was described and figured in detail by Ng & Schubart (2017). The species is most similar to P. crassimanum in most of its external features but the ventral margin of the palm of P. anteactum is gently convex rather than concave ( Fig. 27E versus Fig. 27D ); and the median part of the G1 gently constricted with the proximal and subdistal parts dilated, the distal chitinous part being relatively wider and more truncate ( Fig. 36A–G ) (versus the G1 subdistal part is more dilated than the relatively more slender proximal parts, and the distal chitinous part is proportionately narrower, being more acute and beak-like in P. crassimanum ; Fig. 35B–F, H–L, O–R ).

Biology. The specimens of Ingle & Fernando (1963: 101) were from a brackish water canal in Kirillapone, a low-lying area just 5–6 km west of the main coastal city of Colombo. The types were from somewhere in Colombo. This fits the general habitat preference for many Pseudosesarma species.

Distribution. The species is known only from Sri Lanka thus far ( Ng & Schubart, 2017).

Figures

Fig. 22. Overall habitus, Pseudosesarma species. A, P. edwardsii, lectotype male (17.5 × 16.1 mm) (RMNH-D17a), Mergui Archipelago; B, P. edwardsii, male (13.4 × 11.9 mm) (ZRC 1965.8.2.81), Pulau Pawai, Singapore; C, P. edwardsii, male (12.9 × 11.8 mm) (ZRC 1971.9.24.9), Singapore; D, P. crassimanum, male (15.9 × 14.5 mm) (RMNH-D23313), Singapore; E, P. anteactum, holotype male (16.7 × 14.7 mm) (ZRC 2016.0602), Sri Lanka; F, P. glabrum, holotype male (13.8 × 12.0 mm) (CUSAT 2016-1), Kerala, India; G, P. brehieri, holotype male (17.4 × 15.7 mm) (ZRC 2016.0593), Myanmar; H, P. boulengeri, lectotype male (26.9 × 23.5 mm) (NHM 1919.11.14.1), Basra, Iraq.

Fig. 25. Frontal view of cephalothorax of Pseudosesarma. A, P. edwardsii, lectotype male (17.5 × 16.1 mm) (RMNH-D17a), Mergui Archipelago; B, P. edwardsii, male (13.4 × 11.9 mm) (ZRC 1965.8.2.81), Pulau Pawai, Singapore; C, P. crassimanum, male (15.9 × 14.5 mm) (RMNH-D23313), Singapore; D, P. anteactum, holotype male (16.7 × 14.7 mm) (ZRC 2016.0602), Sri Lanka; E, P. glabrum, holotype male (13.8 × 12.0 mm) (CUSAT 2016-1), Kerala, India; F, P. brehieri, holotype male (17.4 × 15.7 mm) (ZRC 2016.0593), Myanmar; G, P. boulengeri, lectotype male (26.9 × 23.5 mm) (NHM 1919.11.14.1), Basra, Iraq; H, Contusarma bocourti, male (25.3 × 23.3 mm) (ZRC 2000.0952), Bangkok, Thailand; I, Contusarma cheirogonum, neotype male (24.5 × 21.5 mm) (ZRC 1995.225), Bako National Park, Sarawak; J, Miersarma granosimanum, lectotype male (16.9 × 14.8 mm) (NHM 1880.6), Borneo.

Fig. 27. Outer view of chela of Pseudosesarma. A, P. edwardsii, lectotype male (17.5 × 16.1 mm) (RMNH-D17a), Mergui Archipelago; B, P. edwardsii, male (13.4 × 11.9 mm) (ZRC 1965.8.2.81), Pulau Pawai, Singapore; C, P. edwardsii, male (19.4 × 17.3 mm) (ZRC 1971.9.24.8), Singapore; D, P. crassimanum, male (15.9 × 14.5 mm) (RMNH-D23313), Singapore; E, P. anteactum, holotype male (16.7 × 14.7 mm) (ZRC 2016.0602), Sri Lanka; F, P. glabrum, holotype male (13.8 × 12.0 mm) (CUSAT 2016-1), Kerala, India; G, P. brehieri, holotype male (17.4 × 15.7 mm) (ZRC 2016.0593), Myanmar; H, P. boulengeri, lectotype male (26.9 × 23.5 mm) (NHM 1919.11.14.1), Basra, Iraq.

Fig. 30. Male anterior thoracic sternum and pleon of Pseudosesarma. A, P edwardsii, lectotype male (17.5 × 16.1 mm) (RMNH-D17a), Mergui Archipelago; B, P. edwardsii, male (13.4 × 11.9 mm) (ZRC 1965.8.2.81), Pulau Pawai, Singapore; C, P. crassimanum, male (15.9 × 14.5 mm) (RMNH-D23313), Singapore; D, P. glabrum, holotype male (13.8 × 12.0 mm) (CUSAT 2016-1), Kerala, India; E, P. anteactum, holotype male (16.7 × 14.7 mm) (ZRC 2016.0602), Sri Lanka; F, P. anteactum, paratype male (21.2 × 19.7 mm) (ZRC 2016.0603), Sri Lanka; G, P. brehieri, holotype male (17.4 × 15.7 mm) (ZRC 2016.0593), Myanmar; H, P. boulengeri, lectotype male (26.9 × 23.5 mm) (NHM 1919.11.14.1), Basra, Iraq.

Fig. 36. A–G, Pseudosesarma anteactum, holotype male (16.7 × 14.7 mm) (ZRC 2016.0602), Sri Lanka; H–L, P. glabrum, holotype male (13.8 × 12.0 mm) (CUSAT 2016-1), Kerala, India. A, I, left G1 (ventral view); B, J, left G1 (dorsal view); C, D, distal part of left G1 (ventral view, slightly different angles); E, K, ventro-mesial view of distal part of left G1; F, distal part of left G1 (dorsal view); G, L, left G2; H, pleon. Scales: A, B, G = 1.0 mm; C–F, I–L = 0.5 mm; H = 2.0 mm. A–G, after Ng & Schubart (2017: fig. 17); H–L, after Ng et al. (2017a: fig. 4).

Fig. 44. Vulva. A, Pseudosesarma edwardsii, female (16.5 × 15.3 mm) (ZRC 2016.0608), Malaysia; B, Pseudosesarma crassimanum, female (15.9 × 13.8 mm) (ZRC 2000.1768), Malaysia; C, Pseudosesarma crassimanum, female (18.0 × 15.7 mm) (ZRC 2017.1045), Thailand; D, Pseudosesarma anteactum, paratype female (17.5 × 15.4 mm) (ZRC 2016.0603), Sri Lanka; E, Pseudosesarma brehieri, paratype female (14.9 × 13.4 mm) (ZRC 2016.0594), Myanmar; F, Pseudosesarma boulengeri, female (24.2 × 20.0 mm) (ZRC 2014.0335), Iran; G, Contusarma bocourti, female (21.1 × 19.0 mm) (ZRC 2019.1114), Thailand; H, Contusarma cheirogonum, female (26.6 × 23.0 mm) (ZRC 1964.9.28.127), Sarawak; I, Miersarma granosimanum, female (20.1 × 16.4 mm) (ZRC 1965.7.29.166), Malaysia; J, Manarma moeschii, female (19.3 × 17.3 mm) (ZRC 2017.0170), Thailand.

Fig. 35. A–E, Pseudosesarma crassimanum. A–G, lectotype male (16.3 × 14.6 mm) (NHM 1886.52b), Myanmar; H–M, male (15.9 × 14.3 mm) (ZRC 2008.0442), Ranong; N–R, male (15.9 × 14.5 mm) (RMNH-D23313), Singapore. A, N, pleon; B–F, right G1; G, right G2; H–L, O–R, left G1; M, left G2. Scales: A = 2.0 mm; B, G, H, I, M, O, P = 1.0 mm; N = 5.0 mm; C–F, J–L, Q, R = 0.5 mm. After Ng & Schubart (2017: fig. 11).