Munidopsis bairdii ( Smith, 1884 )

Published, First, 2007, Species of the genus Munidopsis Whiteaves, 1784 from the Indian and Pacific Oceans and reestablishment of the genus Galacantha A. Milne-Edwards, 1880 (Crustacea, Decapoda, Galatheidae), Zootaxa 1417, pp. 1-135 : 43-44

Munidopsis bairdii ( Smith, 1884)

Galacantha Bairdii Smith, 1884: 356 .

Munidopsis bairdii .— Baba, 2005: 285 (list of references).— Macpherson & Segonzac, 2005: 17 , fig. 4.

Munidopsis chacei Kensley, 1968: 288 , figs. 1, 3a–b.— Ambler, 1980: 18.

Material examined. W of Sri Lanka, SAFARI 2, Stn 3 (CP05), 2540 m: 1 ovig. F 28.8 mm (MNHN- Ga1562).

Remarks. Munidopsis bairdii is a relatively common species in the Atlantic Ocean ( Macpherson & Segonzac 2005) and it belongs to the group of species having the carapace with a longitudinal row of submedian spines, the posterior-most transverse ridge with spines, the rostrum with lateral spines, the abdomen unarmed, the ocular peduncle movable and short relative to length, the eye-spine directed straight forward, the fixed fin- ger of P1 without a denticulate carina on the distolateral margin, and P2 overreaching P1. The number of submedian spines and their arrangement on the dorsal surface of the carapace has been used to differentiate M. bairdii and M. chacei Kensley, 1968 from South Africa (see Baba 2005): 2-2-2-2-1 (submedian spines) and posterior margin of the carapace with 10 spines in M. bairdii , versus 2-1-2-2-2 (submedian spines) and posterior margin of the carapace with 4 spines in M. chacei . The numerous specimens from the Atlantic Ocean show a certain variation in this arrangement, with the second pair of gastric spines absent or reduced to one spine, and the posterior cardiac spine sometimes paired (as in M. chacei ). Furthermore, in the Atlantic specimens the number of spines on the posterior margin ranges between 4 and 10. The present specimen has only 2-2-1-1 submedian spines and only 2 median spines on the posterior border of the carapace. Another character to differentiate both species (the ratio propodus/dactylus length with the P2 dactylus 3/4 as long as propodus in M. bairdii , being slightly more than half as long in M. chacei ) also shows a certain variation. Therefore, I believe that the specific characters of M. chacei fall within the range of variation of M. bairdii , and as Ambler (1980) suggested, they can be considered as synonyms.

Distribution. Atlantic Ocean, off Delaware Bay, 2738 m ( Smith 1884), off New England, Middle Atlantic Bight, 2125–2933 m ( Wenner 1982), from off British Isles, 55½07’N) to Bay of Biscay (47½30’S) between 2220 and 4262 m (de Saint-Laurent 1985, Macpherson & Segonzac 2005), west of Cape Point, South Africa, 2745 m ( Kensley 1968). Pacific Ocean, from Oregon to Ecuador, between 1986 and 3243 m ( Faxon 1895, Khodkina 1975, Luke 1977, Ambler 1980). The present material extends its range to the Indian Ocean ( Sri Lanka), at 2540 m.