Macrobrachium dienbienphuense Dang and Nguyen, 1972

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 : 634-637

Macrobrachium dienbienphuense Dang and Nguyen, 1972

(figures 14H, I, 20)

Macrobrachium dienbienphuense Dang and Nguyen, 1972: 4 , figure 3 [type locality: Dien Bien Phu , northern Vietnam].

Macrobrachium dienbienphuense Dang, 1980: 384 , figure 220; Liu et al., 1990a: 121, figure 19 (part); Cai and Dai, 1999: 223, figure 9.

Macrobrachium longidigitum Dai, 1984: 248 , figures 18–22 [type locality: Ganlanba, Lancang river, Xishuangbanna, Yunnan, China] (not Macrobrachium longidigitum Bate, 1868 , see Cai and Dai, 1999).

Material examined

North Thailand. Three WW, cl 12.2–13.0 mm, 1 X, cl 11.8 mm ( ZRC 2000.2736 ), afternoon Ban Tho market, outskirt of Chiang Mai city, from Mae Nam Ping river , coll. Y. Cai, 13 June 1998 ; 2 WW, cl 12.8–13.4 mm ( ZRC 2000.2683 ), roadside store from Nan to Chiang Mai, coll. Y. Cai, 11 June 98 ; 1 W, cl 11.2 mm ( ZRC 2000.2732 ), forest stream 95 km north from Nan town, Nan Province, about 15–20 km north from Ban Pon, Nam Gae, north of Ban Sala , near Laos, coll. Y. Cai et al., 11 June 1998 ; 2 WW, cl 10.5–13.0 mm, 3 XX, cl 6.5–8.5 mm, 1 ovigerous X, cl 7.8 mm ( ZRC 2000.2684 ), Mae Lao river, 40 km from Chiang Rai , 19°58∞52.6◊N, 99°41∞46.1◊E, pH 7.8, coll. Y. Cai and Y. Y. Goh, 13 June 1998 ; 3 WW, cl 7.5–9.5 mm, 5 ovigerous XX, cl 9.5–11.5 mm ( ZRC 2000.2720 ), Chiang Dao river, 11 km from Chiang Dao to Chiang Rai , 83 km from Chiang Mai, 19°4∞16.8◊N, 99°32∞25.3◊E, pH 8.1, coll. Cai et al., 12 June 1998 ; 2 XX, cl 10–11 mm, four juveniles ( ZRC 2000.2722 ), Mae Nam Kham river on the way to Mae Sai , 20°07∞31.7◊N, 99°39∞01.7◊E, coll. Y. Cai et al., 12 June 1998 ; three specimens (CU 1997.156), Fang , Chiang Mai, 19 March 1979 ; 3 WW, cl 8–11 mm, 1 ovigerous X, cl 9.5 mm ( ZRC 2000.2731 ), Chiang Dao river, 11 km from Chiang Dao to Chaing Rai , 83 km from Chiang Mai, 19°4∞16.8◊N, 99°32∞25.3◊E, pH 8.1, coll. Cai et al., 12 June 1998 ; 1 W, cl 9.0 mm, 1 X, cl 9.5 mm ( ZRC 2000.2733 ), Mae Nam Ping river, 1–1.5 km below the Nakhon Phing bridge of Chiang Mai city, water warm, turbid, mud bank, slow flowing, 18°58∞25.6◊N, 99°14∞34.1◊E, pH 8.0, coll Y. Cai and Y. Y. Goh, 13 June 1998 .

East Thailand. Four WW, cl 12.5–16.5 mm, 2 XX, cl 7.5 mm, 1 ovigerous X, cl 8.3 mm, eggs 1.1× 0.8 mm ( ZRC 2000.2701 ) , Trat Province, Khlong Huai Raeng, 18 km on road 3271 from Trat to Bo Rai , coll. M. Kottelat et al., 3 December 1993; 4 WW, cl 9.0– 16.2 mm, 2 ovigerous XX, cl 11.0– 11.6 mm ( ZRC 1997.125 ) , Chantaburi Province, downstream of Nam Phliu (waterfall), 12°31∞14.00◊N, 102°10∞35.1◊E, coll. H. H. Tan et al., 14 January 1997; 5 WW, cl 8.7–11.4 mm, 2 XX, cl 9.5–11.8 mm ( ZRC 1997.120 ) , Thailand, Trat Province, Nam Tok Saphan Hin (waterfall), near Ban Saphan Hin , 12°6∞00◊N, 102°42∞55.06◊E, coll. H. H. Tan et al., 15 January 1997; 4 WW, cl 6.0–14.0 mm, 1 X, cl 7.1 mm ( ZRC 1997.113 ) , Thailand, Trat Province, Klong Kwan near Ban Klong Kwan (village), 12°19∞36.6◊N, 102°38∞6.5◊E, coll. H. H. Tan et al., 15 January 1997; 1 W, cl 10.0 mm ( ZRC 1997.126 ) , Thailand, Chantaburi Province, downstream of Nam Tok Phliu (waterfall), 12°31∞14.0◊N, 102°10∞36.1◊E, coll. H. H. Tan et al., 14 January 1997; 1 W, cl 13.0 mm (CU 1997.15), Chanthaburi, 4 December 1988 .

North-east Thailand. Nine WW, cl 10.2–11.7 mm, Phibun, Mangsahan , Ubon Rachathanim Mae Nam Moon, Mangsahan afternoon market, coll. Y. Cai et al., 16 June 1998 ; 20 WW, cl 10.0–12.0 mm ( ZRC 2000.2685 ), Phibun Mangsahan market, 46 km east to Ubon Rachathani, coll. Y. Cai, 16 June 1998 ; 6 WW, cl 10.8–14.0 mm ( ZRC 2000.2687 ), Warin Chamrap market, coll Y. Cai, 17 June 1998 ; 1 W, cl 13.7 mm, That Phanom market on the way from Mukdahan to Nakhon Phanom, coll. Y. Cai et al., 17 June 1998; 32 specimens (CU 1997.67) , Surin, 17 November 1993; 44 specimens (CU 1997.119) , Loei, coll. P. Naiyanetr, 9 April 1987 ; 2 WW, cl 13.8–16.3mm, 1 X, cl 9.0 mm (CU 1997.147), Nong Bua Lam Phun, 11 December 1982; 1 W, cl 9.4 mm, Nakhon Ratchasima, 9 February 1990 ; 1 W, cl 9.5 mm (CU 1997.143), Nakhon, Ratchasima, 6 June 1980; four specimens ( ZRC 2000.2698 ) , Mekong river from Ban Phaeng , 2 km from the village, with murky water, sand and mud bank, coll Y. Cai and Y. Y. Goh, 18 June 1998; one specimen ( ZRC 2000.2694 ) , Trat Phenom market, 52 km from Phanom Nakhon , coll. Y. Cai and Y. Y. Goh, 17 June 1998 .

Central Thailand. Ten WW, cl 9.0–11.0 mm, 5 ovigerous X, cl 6.7–8.3 mm, eggs 1.3×1.0 mm ( ZRC 2000.2693 ), Lop Buri Province, Chai Badan, coll. Y. Cai, 20 June 1998; two specimens ( ZRC 2000.2686 ) , Lam Thakong, outlet of dam at upper Mae Nam Moon , way from Sara Buri to Ratchasima, coll. Y. Cai and Y. Y. Goh, 16 June 1998 .

South Thailand. Three WW, cl 7.5–12.0 mm ( ZRC 2000.2715 ), Narathiwat Province, Ban Sac tributary of Sungai Kolok, ca 19.5 km westwards towards Waeng at T-junction from Sungai Kolok to Waeng and Sungai Padi, 5°47.49∞N, 101°80∞E, pH 7.6, coll H. H. Tan et al., 23 October 1998 ; 1 W, cl 14 mm, 1 ovigerous X, cl 8.3 mm (CU 1997.158), Krabi, coll. P. Naiyanetr, 18 May 1976 ; 1 W, cl 7.5 mm, 1 X, cl 7.4 mm (CU 1997.148), Phatthalung, coll. P. Naiyanetr, 28 May 1976 .

Thai specimens with no specific locality. Two WW, cl 13.2–15.3 mm (CU); 7 WW, cl 10.3–14.5 mm, 2 XX cl 10.4–12.0 mm, 1 X, cl 8.8 mm (ovigerous, eggs 1.7× 1.5 mm) (CU); 2 WW, cl 8.8–16.0 mm, 2 XX, cl 9.8–10.2 mm, 1 ovigerous, eggs 1.4× 0.95 mm (CU 1997.97); 6 WW, cl 9.2–12.9 mm (CU).

Diagnosis

Rostrum convex, reaching to or slightly beyond end of antennular peduncle; rostral formula 3–5+5–9/1–3, dorsal teeth more widely spaced posteriorly than anteriorly. Antennal spine sharp, hepatic spines small, situated below and behind antennal spine. Eyes well developed, about 0.19–0.21 times as long as carapace. Scaphocerite 2.6 times as long as broad, with straight outer margin. Epistome as in figure 20B, trilobed by two depressions. First to third abdominal sternites (figure 20C) with transverse ridge, with median tooth, that of second abdominal sternite largest, that of first less prominent, that of third absent. First pereiopod with fingers as long as palm, chela 0.55 times as long as carpus. Male second pereiopods slender, cylindrical, unequal in length; major male second pereiopod distinctively longer than body; covered with dense tufts of velvety pubescence on palm and fingers; fingers distinctly longer than palm, with 20–32 teeth on both cutting edges, not gaping when closed, tips crossed when fingers closed; palm 3.0–3.7 times as long as wide, carpus elongated, 2.1–3.7 times as long as wide, 0.3 times as long as chela. Third pereiopod reaching beyond scaphocerite by length of entire dactylus; propodus 8.7 times as long as broad, 2.8 times as long as dactylus. Uropodal diaeresis with a spine about half length of outer angle. Eggs 1.10–1.23× 1.5–1.62 mm in diameter.

Remarks

With its elongate second pereiopods, M. dienbienphuense can readily be differentiated from the other members of the M. pilimanus species group, except M. leptodactulus (De Man, 1892). However, it can be distinguished from M. leptodactylus (cf. lectotype: W, cl 16 mm, RMNH D 1801, Buitenzorg (=Bogor), Java, Indonesia, leg. M. Weber, March to September, 1888, designated by Chong, 1989, see figure 17) by the form of the rostrum, which is high and reaches to the end of antennular peduncle or slightly beyond this end (versus narrow, not reaching end of antennular peduncle); the fewer number of postorbital teeth (three to five versus five to six); the larger number of teeth on the cutting edges of the second pereiopods (20–32 versus 15) and the more slender propodus of the third pereiopod (8.7 times as long as broad versus 6.5 times). Macrobrachium dienbienphuense seems to be a widely distributed species, occurring from southern China to southern Thailand.