Macrobrachium malayanum (Roux, 1934), 2004

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 : 604-605

Macrobrachium malayanum (Roux, 1934)

Palaemon (Macrobrachium) pilimanus malayanus Roux, 1934: 32 [type locality: Lasah , Plus valley, Perak, Malaysia].

Macrobrachium geron Holthuis, 1950: 258 , figure 52 [type locality: Banka island off Sumatra, Indonesia]; Holthuis , 1980: 91; Johnson, 1961: 57.

Macrobrachium malayanum: Chong and Khoo, 1987b: 903 ; Ng and Choy, 1990: 13; Ng, 1992: 793.

Material examined

South Thailand. Two ovigerous XX, cl 12.0– 14.3 mm, eggs with eye spot, 1.3× 0.9 mm, ( ZRC 2000.2645 ), Narathiwat Province, Nam Tok Sipo, downstream area, 6°16.06∞N, 101°38.65∞E, coll. H. H. Tan et al., 24 October 1998 .

Diagnosis

Rostrum straight, reaching to or slightly beyond end of scaphocerite; rostral formula: 3–4+5–8/3–6 (mode 3–4). Male second pereiopods unequal in length, dissimilar in form; carpus shorter than merus and chela, fingers shorter than palm; two teeth present on cutting edges of fingers, with two to three smaller ones posterior of proximal large teeth; palm inflated; entire chela of large leg covered with dense carpet of soft, short velvety pubescence; small spinules present on surface of palm; movable spine on uropodal diaeresis longer than outer angle. Ovigerous females with eggs 1.3× 0.9 mm in diameter.

Remarks

Only two ovigerous Thai specimens were available. The specimens agree well with the description by Chong and Khoo (1987b). This is the northernmost record for M. malayanum , and also a new record for Thailand. Macrobrachium malayanum is distributed throughout the Malay Peninsula, Borneo and Sumatra (Roux, 1934; Holthuis, 1950; Chong and Khoo, 1987a; Ng and Choy, 1990; Ng, 1992), and its presence in southern Thailand is not unexpected.