Macrobrachium rathbunae Holthuis, 1950

Valencia, Diego M. & Campos, Martha R., 2007, Freshwater prawns of the genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) of Colombia, Zootaxa 1456, pp. 1-44 : 31-32

Macrobrachium rathbunae Holthuis, 1950

Fig. 17 A–C

Material examined.

Cauca: Guapi. Gorgona Island, 20 May 1986, leg. P. Cala, 1 male, ICN-MHN-CR 1809.

Chocó: Condoto, Vereda El Aguacate, La Vaca stream, affluent of San Juan River, N 5° 5’ 28.6’’, W 76° 37’ 33.5’’, 77 m asl, 20 Mar 2006, leg. M. R. Campos, 1 male, ICN-MHN-CR 2254.— Istmina. San Juan River, 250 m asl, 10 Mar 1994, leg. G. Galvis, 3 males, 1 female, ICN-MHN-CR 1199, 2120.— Vereda San Antonio, La Isidra stream, affluent of San Juan River, N 5° 7’ 57.8’’, W 76° 42’ 3.8’’, 56 m asl, 16 Mar 2006, leg. M. R. Campos, 1 male, ICN-MHN-CR 2245.— Vereda San Antonio, Los Pachos stream, affluent of San Juan River, N 5° 8’ 16.8’’, W 76° 41’ 42.4’’, 63 m asl, 16 Mar 2006, leg. M. R. Campos, 15 males, 4 ovígerous females, ICN-MHN-CR 2246, 2258.— Entre Istmina y Tadó, río Profundó, afluente del río San Juan, 200 m asl, 5 Mar 1994, leg. G. Galvis, 3 males, 2 females, 1 ovígerous, ICN-MHN-CR 1474.— Between Istmina and Tadó, Profundó River, affluent of San Juan River, 200 m asl, 5 Mar 1994, leg. G. Galvis, 3 males, 2 females, 1 ovigerous, ICN-MHN-CR 1474.

Valle del Cauca: Llano Bajo, Aribí stream, 12 Oct 1982, leg. C. Caicedo, 2 males, 5 females, 2 ovigerous, CRBMUV 82006.— Buenaventura. Highway, Sabaleta Alto River, Jan 1980, 1 male, CRBMUV 80034.— Cajambre River, Caimancito, 12 Aug, 1983, leg. C. Caicedo 8 males, 1 female, CRBMUV 83004 A, 83006.— Málaga Bay, Tres Marías, 25 Nov 1985, leg. G. Ramos, 2 females, CRBMUV 85182 A. — Calima. Calima River, 15 Aug 1981, leg. R. Neira, 1 male, CRBMUV 81083.— Creek near Agroforestal Farm, 22 - 23 Oct 1982, leg. C. Caicedo, 12 males, 14 females, 5 ovigerous, CRBMUV 82005, 82011.— Palma Island, in creek, 20 Jun 2003, leg. N. Bolaños & J. F. Lazarus, 4 males 1 ovigerous female, CRBMUV 0 0 3009.

Diagnosis

Rostrum nearly straight, with distal portion directed downward, apex directed slightly upward, usually shorter than scaphocerite, upper margin with 9 to 13 teeth, including 1-2 teeth completely post orbital, first proximal tooth separated from the second one by a large recess, lower margin 3 to 6 teeth; carapace usually smooth, some large specimens slightly pubescent on anterolateral region; abdomen usually smooth, some large specimens slightly pubescent on pleurae, telson and uropoden; telson terminal margin ending in sharp midpoint, flanked by two pairs of spinules, internal pair overreaching midpoint and external pair. First pair of pereopods overreaching scaphocerite with 1/3 of carpus. Second pair of pereopods elongated, prominent, similar in shape and size, with longitudinal rows of spines, overreaching scaphocerite with 1/2 of merus; merus 0.73 to 0.77 x carpus length and 0.83 to 0.91 x palm length; carpus 7.16 to 9.52 x as long as wide, and 1.14 to 1.19 x palm length; palm elongated, cylindrical, 7.76 to 9.33 x as long as wide; fingers thickly pubescent, not gaping when closed, 0.43 to 0.47 x palm length, a tooth on proximal portion in each cutting edge of fingers, followed by denticles to base of finger.

Size. The largest male TL 116.4 mm, CL 30.6 mm; the largest female TL 80.1 mm, CL 20.3 mm; 9 ovigerous females were examined: TL 39.5 to 63.9 mm, CL 8.9 to 15.3 mm, with small and numerous eggs.

Remarks

This species is most similar to Macrobrachium acanthurus ( Wiegmann, 1836) . The two can be distinguished by differences in the rostrum and the second pair of pereopods. The rostrum in M. rathbunae is usually shorter than the scaphocerite, whereas it overreaches the scaphocerite in M. acanthurus . The palm of the second pair of pereopods in M. rathbunae is 7.76 to 9.33 times longer than wide and the fingers are 0.43 to 0.47 times the palm length, whereas the palm in M. acanthurus is 5.62 to 6.26 times longer than wide and the fingers are 0.75 to 0.87 times the palm length. The specimens reported by Prahl, et al. (1984), as Macrobrachium tenellum ( Smith, 1871) , CRBMUV, 82006, are determined as M. rathbunae .

Figures

FIGURE 17. Macrobrachium rathbunae Holthuis, 1950, male, ICN-MHN-CR 1199: A, anterior part of body, lateral view; B, telson, dorsal view; C, second pereopod, lateral view.