Macrobrachium nipponense (De Haan, 1849)

Hanamura, Yukio, Imai, Hideyuki, Lasasimma, Oulaytham, Souliyamath, Pany & Ito, Sayaka, 2011, Freshwater prawns of the genus Macrobrachium Bate, 1868 (Crustacea, Decapoda, Palaemonidae) from Laos, Zootaxa 3025, pp. 1-37 : 18-20

Macrobrachium nipponense (De Haan, 1849)

( Fig. 10 )

Palaemon nipponensis De Haan, 1849: 171 .

Macrobrachium nipponense: Holthuis 1950: 172 ; Chong et al. 1987: 314–316, fig. 1c, d; Liu et al. 1990: 111, fig. 9; Cai & Dai 1999: 220; Hayashi 2000: 468, figs. 398b, 399, 400d–f: Cai & Ng 2002: 78, fig. 20a–f; Li & Liang 2002: 708, 715; Salman et al. 2006: 110, figs. 2, 3; Cai & Shokita 2006: 265; De Grave & Ghane 2006: 204, fig. 2; Li et al. 2007: 128, fig. 50; Gordin & Sudagar 2008: 943 –947.

Palaemon asper Stimpson, 1860: 110 .

Palaemon sinensis Heller, 1862: 528 .

Macrobrachium obtusifrons Dai, 1984: 246 , figs. 6–12.

Macrobrachium meishanense Tan & Lu, 1992: 169 , figs. 1–4.

Material examined. Luang Prabang Province: Ou River, Ngoi District, 3 males (CL 10.5–16.4 mm), 1 ovig. female (CL 13.3 mm), 12 Aug 2000, coll. O. Lasasimma (ex LARReC C 0001); Ou River, Ngoi District, 4 ovig. females (CL 13.5–20.0 mm), 27 March 2001, coll. O. Lasasimma (LARReC C 0 0 11 as Macrobrachium sp. 3); Mekon River, Luang Prabang city, 3 males (CL 14.0– 17.7 mm), 6 Nov 2002, other data unknown; Mekon River, Luang Prabang city, 12 males (CL 10.4–27.0 mm), 18 females (CL 10.5–17.5 mm), 5 ovig. females (CL 15.2–17.5 mm), 25 Jan 2008, coll. Na-Luang Fishery Station. Houaphan Province: Sim River, Vieng Xai District, 14 males (CL 5.0– 20.5 mm), 7 females (CL 6.2–9.2 mm), 16 ovig. females (CL 7.5–12.5 mm), 25 July 2008, hand net, coll. S. Ito et al.

Diagnosis. Rostrum ( Fig. 10 a, b) nearly straight, barely reaching or falling slightly short of anterior end of antennal scale, armed dorsally with 10–13 teeth including 2 or 3 placed posterior to orbital margin, ventrally with 2 or 3 teeth; antennal spine just behind lateral margin, apex extending slightly beyond antennal lobe; hepatic spine as large as or slightly larger than antennal spine, situated posteriorly, just below level of antennal spine.

Antennal scale 0.6–0.8 times as long as carapace, 2.9–3.1 times as long as wide.

Sixth abdominal somite 1.3–1.6 times as long as fifth, pre-anal carina indistinct, represented by obtuse ridge. Telson 1.4–1.7 times as long as sixth abdominal somite, posterior end sub-triangular with moderately sharp point, with 2 pairs of ordinary sub-terminal spines in addition to 2 pairs of dorsolateral spines, anterior pair of latter spines situated at mid-length.

Second pereopods ( Fig. 10 a, c) sub-equal in length and similar in shape, about twice of total body length in larger males (CL> 20 mm), extending beyond antennal scale by half length of merus and onwards, covered with small spinules on almost entire length; carpus about 1.4 times longer than merus, about 0.8 times as long as chela; fingers about 0.65 times as long as palm, the former covered with short setae along its cutting edges. Second pereopods of adult females (CL> 15 mm) shorter than that of males, with mero-carpal articulation reaching anterior end of first antennular peduncle segment. Third pereopod with propodus 2.55–3.3 times as long as dactylus, latter becoming proportionately long with increasing body size.

Exopod of uropod slightly longer than endopod, movable spine on diaeresis ( Fig. 10 d) slightly longer than lateral projection.

Eggs. Eggs carried by females numerous but noticeably small in size, non-eyed eggs measuring 0.6–0.7 x 0.7– 0.8 mm.

Remarks. The Japanese estuarine and freshwater populations of M. nipponense have been reported to have different reproductive characteristics (e.g., see Mashiko & Numachi 2000). Otherwise, Hayashi (2000) observed some morphological differences among local Japanese populations; i.e., fingers of the second pereopod having dense velvety setae (vs. sparse setae) or the presence of a sub-marginal (vs. post-marginal) antennal spine. Thus, we may be dealing with a species complex under M. nipponense , and future studies are strongly required along its geographical scale.

Macrobrachium nipponense is regarded as an East Asian endemic species, originally distributed in Japan, China, and Taiwan ( Hayashi 2000), although it has now spreads widely in Asia from Japan through Iraq as a result of possible aquaculture activities (cf. Chong et al. 1987c; Wowor et al. 2004; Gorgin & Sudagar 2008). Macrobrachium nipponense is believed to be an invasive species in Laos and was probably introduced into the country at several sites in association with aquaculture business (see also “Remarks” under M. superbum ).

Distribution. Macrobrachium nipponense has been recorded from Japan, China, Taiwan, Philippines, Vietnam, Laos, Malaysia, Singapore, Myanmar, Kazakhstan, Iran, and Iraq (Chong et al. 1987; Wowor et al. 2004; Cai & Shokita 2006; De Grave & Ghane 2006, Gorgin & Sudagar 2008; present study).

Figures

FIGURE 10. Macrobrachium nipponense, male (CL 27.0 mm) (a, c, d) and male (CL 19.0 mm) (b) collected from Mekong River, Luang Prabang Province, Laos: a, entire body; b, carapace and cephalic appendages, lateral view; c, fingers of right second pereopod, mesial view; d, uropodal diaeresis, lateral view.