Macrobrachium americanum Bate, 1868

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 : 8-10

Macrobrachium americanum Bate, 1868

Fig. 3 A–C

Macrobrachium americanum Bate, 1868: 363 .

Macrobrachium americanum, Holthuis, 1952: 128 .— Prahl et al., 1978: 55.— Méndez, 1981: 73.— Rodríguez, 1981: 47.— Prahl et al.,1984: 47.— Abele & Kim, 1989: 5.— Wicksten, 1989: 13. (For detailed synonymy refer to Holthuis, 1952).

Material examined

Cauca: Guapi. Gorgona Island. Jan - Feb 1961, leg. F. Medem, 2 males, 3 females, 1 ovigerous, ICN- MHN-CR 0 0 0 1 - 0005.— Gorgona Island, 20 May 1979, 1 male, CRBMUV 79034.— Gorgona Island, 15, 18, 20 May 1986, leg. P. Cala, 3 males, 3 females, 1 ovigerous, ICN-MHN-CR 1807, 1808, 2116.— Gorgona Island, Airport, in creek, 28 Mar 1980, 1 ovigerous female, CRBMUV 80001.— Gorgona Island, La Azufrada stream, 25 May 1978, 1 male, 2 females, CRBMUV 78005.— Temuey, Guapi River, 21 Oct 2004, leg. D. M. Valencia & M. R. Campos, 4 males, 9 females, ICN-MHN-CR 2185, 2186.

Chocó: Ensenada de Utría. La Aguada, 17 Dec 1979, 2 ovigerous females, CRBMUV 79030.— Bajo Baudó, Pepe River, 17 Jun 1979, leg. H. Prahl, 1 male, CRBMUV 79019.— Pizarro, 8 Jul 1981, leg. N. Toro & M. Marín, 1 male, CRBMUV 81084.

Valle del Cauca: Bahía Málaga. in stream, 29 Dec 1985, leg. D. Garcés, 1 male, CRBMUV 85197.— La Alegría stream, 24 Dec 1985, 1 male, 3 females, CRBMUV 85068.— Las Tres Marías, 30 Aug 1980, 1 male, 3 females, CRBMUV 80005.— Las Tres Marías, 25 Nov 1985, leg. G. Ramos, 6 males, 2 females, CRBMUV 85182.— Las Tres Marías, in creek, 8 Dec 1985, 3 females, CRBMUV 85067.— Buenaventura, Dagua River, 19 Apr 2003, 3 males, 2 females, Universidad de los Andes.— Cajambre River, Caimancito, 12 Aug 1983, 2 males, 3 females, CRBMUV 83004.— Dagua, Dagua River, 750 m asl, 22 Nov 1995, 2 males, ICN- MHN-CR 1597.

Diagnosis

Rostrum lanceolate, apex curved upward, as long as or shorter than antennular peduncle, upper margin with 10 to 13 teeth spaced regularly, including 3-5 teeth completely post orbital, lower margin 2 to 5 teeth; carapace smooth; abdomen smooth; telson terminal margin ending semicircular with one pair of internal and external reduced spines, not overreaching terminal margin of telson. First pair of pereopods overreaching scaphocerite with 3/4 of carpus. Second pair of pereopods elongated, prominent, similar in shape and size, overreaching scaphocerite with 1/3 to 1/2 of merus; merus 1.09 to 1.12 x longer than carpus, and 0.53 to 0.62 x palm length; carpus 2.04 to 2.34 x as long as wide and 0.50 to 0.55 x palm length; palm prominent, 3.25 to 4.74 x as long as wide, 2.60 to 3.54 x as long as high; fingers 0.87 to 1.0 x palm length, gaping when closed, a prominent tooth on midcutting edge of mobile finger, and another one on proximal portion of cutting edge of fixed finger, usually followed by 3 to 4 denticles on each base of finger.

Size. The largest male TL 220.7 mm, CL 68.4 mm; the largest female, TL 152.1 mm, CL 47.6 mm; 5 ovigerous females were examined: TL 75.0 to 152.1 mm, CL 21.6 to 47.6 mm, with small and numerous eggs.

Remarks

This species is most similar to Macrobrachium carcinus ( Linnée, 1758) , sometimes it is difficult to differentiate specimens of these two species. For this reason, Holthuis (1952) suggested that these two species should be considered as subspecies. However, in the Colombian material we found that these two species have differences in the length of the fingers of the second pair of pereopods: the fingers in M. americanum are as long as or slightly shorter than the palm, whereas they are slightly longer than the palm in M. carcinus . The species M. americanum was reported from Escalerete River, department of Valle del Cauca and the specimens were deposited at the CRBMUV by Prahl et al. (1984). In a recent examination of Prahl et al ’s material at the CRBMUV the specimens could not be found.

Figures

FIGURE 3. Macrobrachium americanum Bate, 1868, male, ICN-MHN-CR 1808: A, anterior part of body, lateral view. Male, ICN-MHN-CR 1807: B, telson, dorsal view; C, second pereopod, lateral view.