Polyonyx hendersoni Southwell, 1909

(Fig. 3D)

Restricted synonymy:

Polyonyx hendersoni Southwell, 1909: 117, figs. 6–9.— Gravely, 1927: 141, pl. 20 fig. 11.— Johnson, 1958: 98, 112.— Haig, 1974: 380.—Sankolli, 1966: 309, fig. 8.— Tirmizi et al., 1982: 3, fig. 8, pl. VIII.— Patel et al. 2022: 37.

Material examined. FSI/ CRUST: 234, 1 female (CL 6.1 mm, CW 6.6 mm), 18°14.0’N, 84°10.1’E, 42–43 m, on desmosponges, coll. K. Silambarasan, 15 December 2020 .

Distribution. Sri Lanka and Pakistan (Southwell 1909); India (Patel et al. 2022). Now recorded again from India after a long gap of 94 years from Visakhapatnam, Bay of Bengal.

Commensalism. This species usually observed in intertidal areas inhabiting exclusively the water ducts of Desmospongiae. In the present study, P. hendersoni was collected from the Desmospongiae on the northeast coast of India. Hiller et al. (2010) collected P. hendersoni from white sponges from intertidal areas of St George Island, Goa. Similarly, Beleem et al. (2017) also reported P. hendersoni from cavities of yellow sponges from the intertidal zone of the Gulf of Kutch, Gujarat.

Remarks. This species is endemic to the Indian Ocean and closely resembles Polyonyx splendidus (Sankoli, 1963), which also occurs in the cavities of sponges. Polyonyx splendidus differs from P. hendersoni by the meral lobe of the chelipeds, carpus and chelipeds covered with plumose setae (Hiller et al. 2010).