Macrobrachium superbum ( Heller, 1862 )

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 : 26-27

Macrobrachium superbum ( Heller, 1862)

( Fig. 14 )

Palaemon superbus Heller, 1862: 528 .

Macrobrachium superbum: Holthuis 1950: 139 ; Liu et al. 1990: 105, Fig. 3 ; Cai & Dai 1999: 221, fig. 7; Li et al. 2007: 134, fig. 53.

Material examined. Houaphan Province: Sim River, Vieng Xay District, 10 males (CL 5.4–8.0 mm), 25 July, 2008, hand net, coll. S. Ito et al.

Diagnosis. Rostrum ( Fig. 14 a) extending slightly beyond antennular peduncle but not overreaching antennal scale, dorsal margin nearly straight, with 10–13 teeth including 2 or 3 situated posterior to orbital margin, ventral margin with 2 or 3 teeth; antennal lobe moderately developed, antennal spine marginal, extending slightly beyond antennal lobe; hepatic spine smaller than antennal spine, placed posteriorly, slightly below level of antennal spine.

Sixth abdominal somite about 1.5 times as long as fifth one, pre-anal carina hardly visible; first 2 abdominal sternites with marked media projection but not on third; fourth pleuron rounded posteriorly, that of fifth sub-rectangular but with no projection/point. Telson 1.3–1.4 times as long as sixth abdominal somites, posterior end triangular with 2 pairs of ordinary sub-terminal spines, 2 pairs of dorsolateral spines, anterior pair of latter ones placed around mid-length.

Antennal scale 0.7–0.8 times as long as carapace, about 3 times as long as wide. Epistome bi-lobed. Third maxilliped reaching end of first segment of antennular peduncle, distal segment slightly shorter than penultimate.

First pereopod overreaching antennal scale by distal part of fingers, latter as long as or slightly shorter than palm. Second pereopods ( Fig. 14 a, b) sub-equal in length and similar in shape, length shorter than total body length and extending beyond antennal scale by distal 1/5–1/3 of carpus and onwards; merus slightly shorter than carpus, latter shorter than chela, 1.6–2.0 times as long as palm; fingers 1.2–1.4 times as long as palm, no tubercles or teeth present on cutting edges. Third pereopod with propodus ( Fig. 14 c) 2.3–2.7 times as long as dactylus, with 6 or 7 somewhat widely set spines on posterior margin.

Appendix masculina ( Fig. 14 d) slightly less than twice length of appendix interna, with numerous stiff setae on mesial surface. Uropodal exopod sub-equal in length to endopod, movable spine on diaeresis ( Fig. 14 e) longer than lateral projection.

Remarks. According to published literature ( Zhang & Sun 1981; Liu et al. 1990; Cai & Dai 1999), M. superbum often co-occurs with M. nipponense in various localities of China. Specimens assigned to this species closely resemble young M. nipponense . Among specimens captured in the Houaphan Province in north-eastern Laos, those with the palm of the second pereopod shorter than the fingers without tooth on its cutting edges were referred to as M. superbum . Other specimens of comparable body sizes having the palm of sub-equal length to or slightly longer than fingers as well as the cutting edges possessing small tubercles at base were attributed to M. nipponense . It is most probable that M. superbum have been introduced accidentally in Laos in association with aquaculture activities together with M. nipponense .

Distribution. Macrobrachium superbum was established from south-eastern China near Shanghai and has then been recorded throughout China ( Li et al. 2007).

Figures

FIGURE 3. Macrobrachium dienbienphuense, male (CL 17.7 mm) collected from Luang Prabang Province, Laos, entire body. Scale bar = 10 mm.

FIGURE 14. Macrobrachium superbum, male (CL 6.4 mm) collected from Sim River, Houapan Province, Laos: a, entire body; b, chela of left second pereopod, lateral view; c, left third pereopod, lateral view; d, appendix masculina, mesial view; e, uropodal diaeresis, lateral view.