Macrobrachium meridionalis Liang & Yan, 1983

Guo, Zhao-Liang & He, Shun-Lian, 2008, One new and four newly recorded species of the genus Macrobrachium (Decapoda: Caridea: Palaemoindae) from Guangdong Province, southern China, Zootaxa 1961 (1), pp. 11-25 : 18-21

Macrobrachium meridionalis Liang & Yan, 1983

( Figs. 4–6 )

Macrobrachium meridionalis Liang & Yan, 1983: 213 , fig. 2 [type locality: Jingjiang river, Chengmai County, Hainan Island, southern China]; Liu et al., 1990: 115, fig. 13; Yeo et al., 1999: 227, figs. 15, 16.

Material examined. 1 male, tl. 85.0 mm, cl. 27.0 mm, Dali Town , Foshan City, 15 March 2003 ; 4 females, tl. 50.0– 65.5 mm, cl. 14.5–17.5 mm, 3 males, tl. 83.0– 86.5 mm, cl. 26.9–27.5 mm, Dongping river , near Foshan City, 18 May 2004 ; 2 males, tl. 65.0– 74.5 mm, cl. 15.2–28.0 mm, Shatoujia Town , Foshan City, 21 October 2004 ; 1 ovigerous female, tl. 56.5 mm, cl. 15.4 mm, Xijiang River near Shunde, Foshan City, 24 March 2004 ; 1 male, tl. 77.8 mm, cl. 23.8 mm, Xijiang River near Deqin City, 17 May 2005 ; 1 male, tl. 71.7 mm, cl. 22.3 mm, Xijiang River near Zhaoqin City, 18 May 2005 ; 12 females, tl. 46.0– 75.5 mm, cl. 13.2–23.1 mm, 24 males, tl. 48.0– 87.5 mm, cl. 15.2–26.0 mm, Huangqi fish market, 18 June 2005 .

Diagnosis. Rostrum reaching as far as or extending beyond end of antennular peduncle, upper margin slightly convex above eyes; rostral formula: 4–7 + 6–8/2–4, rl. about 0.40–0.50 cl. Cephalothorax, abdomen and telson smooth, without microspinules. Second pereiopods subequal in both sexes, all segments rough, covered with appressed scales, those on inner margin spiniform, finger about 0.44–0.71 times as long as palm, cutting edges of fixed finger with 2–4 teeth, basal tooth formed of 4–12 (usually 4 or 5) denticles, movable finger with 3–6 tooth in proximal half to two–thirds; carpus shorter than palm, about 0.62–0.91 times as long as palm, palm slightly compressed, subcylindrical, 3.3–4.9 times as long as width; carpus cylindrical, about 1.1–1.3 times as long as merus; merus about 1.1–1.6 times as long as ischium. Egg size: 0.42–0.47 X 0.51– 0.65 mm in diameter.

Live coloration. This prawn seems to be quite variable in color, with at least three color variations. In specimens collected from rocky beds, under pebbles and stones, the body and appendages are buff with irregular dark brown or red spots ( Fig. 4 ). In specimens collected from sandy substrates, the body is very dark brown, the cephalothorax has yellow spots, and the abdomen and telson have irregular yellow stripes and spots. Those from localities with a much aquatic vegetation have a bluish-green body with irregular dark brown spots. The eggs are grass green.

Remarks. The first record of Macrobrachium meridionalis Liang & Yan, 1983 was from Chengmai County, Hainan Island, southern China. The description was based on three small specimens ( Liang & Yan, 1983). Recently, Yeo et al. (1999), after reexamining the paratype and observing the specimens from Peninsular Malaysia, provided additional details of the morphology of M. meridionalis and expanded its distribution in Peninsular Malaysia. The present specimens essentially match the definition of the present species as given by Liang & Yan (1983), Liu et al. (1990) and Yeo et al. (1999). There are some minor differences compared to the type specimens. The rostral formula of the Guangdong specimens is 4–7 + 6–8/2–4 versus 5–6 + 7–8/ 2–3 in the types. The tooth arrangement of the cutting edges of the fingers of the major male second pereiopod is quite variable; the fixed finger has 2–4 teeth, the basal tooth is formed of 4–12 (usually 4 or 5) denticles, movable finger with 3–6 tooth in proximal half to two-thirds ( Fig. 5 ). There is a distinct longitudinal groove along the each surface of the palm of second pereiopods of the fully developed adult male ( Fig. 6 ). Yeo et al. (1999: 227) also found a very distinct sulcus along the length of the carpus and the proximal half of the palm, and noted other differences such as a relative longer and slender finger of the second pereiopods. This is the first record in the Guangdong Province.

When living animals are attacked, the second pereiopods are easily broken off the body. Therefore, most living specimens sold in markets and most preserved specimens have lost their second pereiopods.

This species is commercially important in Guangdong Province. It is fished for home and restaurant consumption as a special dish and sometimes it is sold in large quantities in fish markets. In markets, the price of this species is double that of other freshwater prawns such as M. nipponense , because of their size and the excellent flavour. Local commercial fishermen call it Shi xia (meaning stone prawn) due to its habitat, i. e., usually in crevices among stones.

Distribution and habitat. Southeastern China (Guangdong and Hainan Provinces) and Malaysia (Pulau Tioman). The species seems to be restricted to relatively slow flowing rivers above the reach of tidal influence.

Figures

FIGURE 4. Photographs of living specimen of Macrobrachium meridionalis. A, C, male. B, ovigerous female.

FIGURE 5. Fingers of male second pereiopod of Macrobrachium meridionalis, showing morphological variation of the arrangement of the teeth on the cutting edges. Scale = 5 mm.

FIGURE 6. Second pereiopod of Macrobrachium meridionalis. A, entire in outer view. B, entire in inner view. C, palm and fingers of male major second pereiopod (outer surface), showing groove on the palm.