Macrobrachium equidens Dana, 1852

Cai, Y., Naiyanetr, P. & Ng, P. K. L., 2004, The freshwater prawns of the genus Macrobrachium Bate, 1868, of Thailand (Crustacea: Decapoda: Palaemonidae), Journal of Natural History 38 (5), pp. 581-649 : 589-590

Macrobrachium equidens Dana, 1852

Palaemon equidens Dana, 1852: 26 [type locality: Singapore]. Palaemon sundaicus: Lanchester, 1902: 568 ; Kemp, 1918a: 261. Macrobrachium sundaicus: Suvatti, 1937: 49 ; 1967: 140. Macrobrachium equidens: Holthuis, 1950: 162 , figure 36; 1980: 90; Johnson, 1961: 56; Lumubol,

1980: 501, figure (under the name of M. idae , see Remarks under M. idae ); Naiyanetr, 1980:

17; 1992: 18; 1998: 32; Chace and Bruce, 1993: 25, figure 4; Yeo et al., 1999: 226.? Macrobrachium nipponense: Lumubol, 1980: 504 , figure.

Material examined

Central Thailand. Two WW, cl 22.6–23.9 mm, 1 ovigerous X, cl 21.9 mm (CU 1997.233), Nonthaburi, 10 February 1980; seven specimens , cl 9.0– 14.4 mm (CU 1997.234), Samut Prakarn , 15 March 1981 ; 1 W, cl 21.6mm, 9 ovigerous X, cl 15.4–19.9mm (CU 1997.235), Samut Sakhon, 30 October 1980 ; 3 WW, cl 13.6–20.7 mm, 2 XX, cl 11.8–18.6 mm (CU 1997.236), Samut Sakhon, 13 December 1980 ; 7 ovigerous XX, cl 12.6–16.0 mm (CU 1997.237), Samut Prakarn , 18 October 1980 ; 3 WW, cl 14.7–19.4 mm, 1 X, cl 20.5 mm (CU 1997.238), Samut Songkhram, 21 March 1980 ; 4 XX (2 ovigerous), cl 19.0– 20.6 mm (CU), Samut Songkhram, 13 December 1980 ; 3 ovigerous XX, cl 15.3–22.0 mm (CU 1997.240), Nonthaburi, May 1980 .

South Thailand. Ten WW, cl 14.0–20.0 mm, 29 ovigerous XX, cl 20–21.5 mm (CU 1997.9), Narathiwat, 15 June 1983 ; 9 WW, cl 13.0–17.0 mm, 26 XX (2 ovigerous), cl 10.0– 17.5 mm (CU), Narathiwat (from market), 11 January 1993 ; 1 W, cl 14.0 mm (CU 1997.14), Ranong (from mangrove), 27 July 1988 ; 4 WW, cl 20.0–24.0 mm, 2 ovigerous XX, cl 17.0 mm (CU), Trang, 29 October 1988 ; 2 WW, cl 20–24 mm, 1 ovigerous X, cl 16 mm ( ZRC 2000.2717 ), Trang, coll. P. Naiyanetr, 29 October 1988 .

Thai specimens with no specific locality. Two XX, cl 15.1–20.4 mm (CU 1997.75); 8 ovigerous XX, cl 20.5–28.0 mm (CU 1997.71); 19 ovigerous XX, cl 18.0–21.0 mm (CU 1997.81); 43 specimens (CU 1997.83).

Remarks

Macrobrachium equidens is usually a brackish water species, with smaller specimens being commonly found in mangrove creeks. The species is characterized by its upturned and sinuous rostrum. The variation in rostral form and body colour is considerable and this can sometimes cause taxonomic confusion. Macrobrachium equidens has previously been recorded from southern and central Thailand by Lanchester (1902), Kemp (1918a), Suvatti (1937), Holthuis (1950) and Naiyanetr (1980). It is known from a very wide area in the Indo-West Pacific, from Madagascar to the Solomon Islands. On the basis of his figures, specimens identified as ‘ Macrobrachium nipponense ’ by Lumubol (1980: 504) probably belong to this species as well.