Macrobrachium yui Holthuis, 1950

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 : 611-613

Macrobrachium yui Holthuis, 1950

(figure 10)

Palaemon brevicarpus var. heterochirus Yu, 1936: 305 , figures 1, 2 [type locality: Ninger , Puer County, Yunnan, China].

Macrobrachium yui: Holthuis, 1950: 211 ; Liu et al., 1990: 123, figure 20; Naiyanetr, 1992: 18; Cai and Dai, 1999: 237.

Macrobrachium yeti Dang, 1975: 67 , figure 1 [type locality: northern Vietnam]; Dang , 1980: 386, figures 221.

Material examined

North Thailand. One X, cl 8.0 mm, 1 ovigerous X, cl 12.6, eggs 1.9× 1.5 mm ( ZRC 2000.2708 ), Mae Hong Song: Nae Mae Yuam basin: Nam Tok Natae Rachan , innamed torrent, 16 road-km east of Ban Mae La Noi , coll. M. Kottelat and K. Kubota, 9 April 1998 ; 1 X, cl 13.3 mm ( ZRC 2000.2707 ), Mae Hong Son, Nam Mae Sarieng at dam upriver of Mae Sarieng , coll. M. Kottelat and K. Kubota, 9 April 1998 ; 1 X, cl 13.0 mm, 1 ovigerous X, cl 7.5 mm, eggs 1.2× 0.85 mm ( ZRC 2000.2697 ), Carp Paliu Cheh Mae Nam Khwae Noi basin, Nam Khung near Ban Huai Pak Khungm coll. M. Kottelat and K. Kubota, 4 April 1998 ; 1 W, cl 20.0 mm (CU 1997.95), Mae Hong Son, 7 December 1980 ; 1 W, cl 24.0 mm ( ZRC 2000.2730 ), Mae Hong Son, 23 March 1978 ; 2 WW, cl 11.5–27.0 mm, 1 X, cl 15.0 mm (CU 1997.111), Mae Hong Son, coll. C. Vidthayanon, no date; 3 WW, Chiang Dao, Chiang Mai, no data ; 23 specimens (CU 1997.88), Chai Badan and Lopburi, coll. P. Naiyanetr, 16 June 1982 ; 2 WW, cl 26–27 mm, 4 XX, 13–20 mm ( ZRC 2000.2654 ), Pai river near Lod Cave , Mae Hong Son, coll. C. M. Yang and T. B. Lim, 9 September 1998 ; 3 WW, cl 13.5–15 mm, 4 XX, cl 11–17 mm ( ZRC 2000.2655 ), Pai river near Lod Cave , Mae Hong Son, coll. C. M. Yang and T. B. Lim, 9 September 1998 .

Diagnosis

Rostrum slightly convex, reaching to base of third segment of antennular peduncle, or to end of this segment. Rostral formula: 3–5+5–8/1–3. Hepatic spine small. Antennular peduncle 0.4 times as long as carapace. Scaphocerite 2.6 times as long as wide. First pereiopod reaching with one-third of carpus beyond distal end of scaphocerite; chela with fingers shorter than palm, 0.55 times as long as propodus. Second pereiopods of male unequal in length, similar in form. Major second pereiopod reaching with one-third of carpus beyond distal margin of scaphocerite; carpus slightly shorter than merus, palm inflated, longer than merus, slightly shorter than fingers; fingers with five to six teeth on proximal third of cutting edge. Whole leg covered by tiny spinules. Second pereiopods of female much shorter than that of male, equal in length, similar in form. Third pereiopod reaching beyond scaphocerite by half length of propodus, propodus eight times as long as broad, three times as long as dactylus; dactylus with a long, slender claw, 3.2 times as long as broad. Uropodal diaeresis without spine in adult but with a small spine in young. Ovigerous female with eggs 1.5–1.6× 1.1–1.2 mm in diameter.

Habitats

Macrobrachium yui is commonly found in fast flowing waters, and it seems like to hide in the crevices between granitic rock.

Remarks

Macrobrachium yui was originally described from Yunnan in southern China. The species was previously reported from Thailand by Naiyanetr (1992).

Cai and Dai (1999) pointed out that Macrobrachium yeti Dang, 1975 , is very close to M. yui and are very difficult to distinguish. Only two differences separate M. yeti from M. yui , namely, the postorbital carapace teeth number (three in M. yeti and four to five in M. yui ) and the form of the second pereiopods, which is slightly more slender in M. yeti , with various joints having slightly different proportions. The proportion of the various joints in M. yeti , however, fall into the known intraspecific variation of M. yui . Hence, M. yeti must be regarded as a junior synonym of M. yui .