Macrobrachium amazonicum (Heller, 1862)

Fig. 2 A–C

Palaemon amazonicus Heller, 1862: 418.

Macrobrachium amazonicum, Holthuis, 1952: 18.— Medina & Sobrino, 1975: 40.— Rodríguez, 1980: 115.— Rodríguez, 1981: 45, 47.— Rodríguez, 1982: 379.— Kensley & Walker, 1982: 3.— Magalhães, 1985: 247.— Magalhães & Walker, 1988: 279.— López & Pereira, 1996: 48.— Magalhães, 2002: 1092.— Melo, 2003: 340.— García - Dávila & Magalhães, 2004: 666.

(For detailed synonymy refer to Holthuis, 1952).

Material examined

Amazonas: Puerto Nariño. May 1957, leg. Nicéforo María, 4 males, 2 females, MLS 9.— Amazon River, 85 m asl, 1 Jan 1972, leg. H. Hasima & H. T. Boschung, 12 males, 18 females, 2 ovigerous, ICN-MHN- CR 0033.— Patrullero Island, Amazon River, 4 Jan 1972, leg. H. T. Boschung, 1 male, 2 females, ICN-MHN- CR 1796.

Arauca: Caño Limón, Agua Verde Lake, 15 Jul 1991, leg. G. Galvis, 61 males, 89 females, 15 ovigerous, ICN-MHN-CR 1793.— Tame Highway, Fortúl creek, 6 Mar 1977, leg. P. Cala, 2 females, ICN-MHN-CR 1817.— La Saya, Cabuyare creek, 10 Mar 1987, leg. P. Cala, 2 males, 2 females, 1 ovigerous, ICN-MHN-CR 1739.

Casanare: Without precise locality, 19 Feb 1974, leg. P. Cala, 7 males, 27 females, 11 ovigerous, ICN- MHN-CR 0058.— Guachiría River, 12 Feb 1974, leg. P. Cala, 2 males, 4 females, 1 ovigerous, 1 juvenile, ICN-MHN-CR 1801.— Maní. Charté River, 175 m asl, Feb 1971, leg. P. Cala, 17 males, 14 females, ICN- MHN-CR 0027.— Curital creek, 175 m asl, 19 Feb 1971, leg. P. Cala, 9 males, 5 ovigerous females, ICN- MHN-CR 0028.— Paz de Ariporo. Boquerón, Garza creek, 275 m asl, 12 Feb 1974, leg. P. Cala, 5 males, 5 females, 4 ovigerous, ICN-MHN-CR 0054.— Cantagallo creek, affluent of Ariporo River, 14 Feb 1974, leg. P. Cala, 1 male, 1 ovigerous female, ICN-MHN-CR 1802.— Hato Corozo, Aguas Verdes creek, 275 m asl, 15 Feb 1974, leg. P. Cala, 1 male, ICN-MHN-CR 0056.— Hato Las Canarias, La Hermosa creek, 275 m asl, 17 Feb 1974, leg. P. Cala, 12 males, 3 females, 1 ovigerous, ICN-MHN-CR 0057.— San Luis de Palenque, Hato Altamira, Suárez creek, 200 m asl, 13 Feb 1974, leg. P. Cala, 4 males, 3 females, 2 ovigerous, ICN- MHN-CR 0 0 55. — Between Trinidad and Rondón, Guachiría River, 20 Feb 1974, leg. P. Cala, 1 male, 3 females, 2 ovigerous, ICN-MHN-CR 1805.

Guaviare: Guaviare River, 17 Aug 1989, 7 males, 5 females, Universidad de Antioquia.— San José del Guaviare. Barranco, La Sal creek, 200 m asl, 20 Jun 1997, leg. N. C. Garzón, 1 male, 5 females, 1 ovigerous, 14 juveniles, ICN-MHN-CR 1677.— Flauta creek, 15 Aug 1989, 1 male, 3 females, Universidad de Antioquia.

Meta: La Macarena, Vereda Alto Raudal, in lake affluent of Santo Domingo River, 490 m asl, 15 Feb 1988, leg. P. Cala, 5 males, 3 females, 2 ovigerous, ICN-MHN-CR 0881.— Puerto Gaitán, Vereda San Miguel, Meta River, 150 m asl, 20 Aug 1984, leg. J. Madrid, 5 females, ICN-MHN-CR 1379.— Puerto López. El Picacho creek, affluent of Meta River, 450 m asl, 21 Sep 1989, leg. M. Morales, 9 males, 8 females, ICN-MHN-CR 1130.— Vereda Bajo Menegua, Lagunazo Farm, 290 m asl, 18 Apr 1984, leg. R. Restrepo, 1 male, 1 ovigerous female, ICN-MHN-CR 0572.— Guachiría River, Curimira creek, affluent of Meta River, 6 Feb 1974, leg. P. Cala, 4 males, 2 females, 1 ovigerous, 1 juvenile, ICN-MHN-CR 1797.— Guayuriba River, 2 Jul 1971, leg. P. Cala, 1 male, 5 females, 1 ovigerous, 1 juvenile, ICN-MHN-CR 0030.— Vereda Menegua, 200 m asl, 27 Feb 1990, leg. G. Galvis, 8 males, 10 females, 4 ovigerous, ICN-MHN-CR 1468.— Cafam Llanos, Mata-Mata Lake, 180 m asl, 20 Mar 2004, leg. M. Leyva, 1 male, ICN-MHN-CR 2182.— Mozambique, Humacita Lake, 184 m asl, 2 Jul 1971, leg. P. Cala, 7 males, 48 females, 19 ovigerous, 3 juveniles, ICN-MHN-CR 0031.— Mozambique, Humacita Lake, 200 m asl, 23, 24 Jun 1972, leg. F. Flórez, 3 males, 24 females, 19 ovigerous, ICN-MHN-CR 0 956, 0957.— Mozambique, Humacitas Lake, 184 m asl, 6 Nov 1972, leg. F. Flórez, 17 males, 80 females, 14 ovigerous, ICN-MHN-CR 0052.— Puerto Rico, Vereda Caño Alfa, Matecaña Lake, Parque Natural de la Macarena, 225 m asl, 18 Jan 1985, leg. C. Useche, 4 females, ICN- MHN-CR 0 610.

Diagnosis

Rostrum sinuous, convex on orbital region, distal portion directed upward, overreaching scaphocerite, upper margin with 7 to 14 teeth, the proximal teeth with less recess between them than the distal ones, including 1 tooth completely post orbital, lower margin 5 to 10 teeth; carapace smooth; abdomen smooth; telson terminal margin ending in sharp midpoint, flanked by two pairs of spinules, internal pair not overreaching midpoint. First pair of pereopods overreaching scaphocerite with distal portion of fingers. Second pair of pereopods elongated and slender, similar in shape and size, longitudinal rows of spinules from ischium to palm, overreaching scaphocerite with 1/2 to 3/4 of carpus; merus 0.60 to 0.68 x carpus length, and 1.28 to 1.92 x palm length; carpus 1.10 to 1.67 x chela length; fingers 0.75 to 0.89 x palm length; fingers pubescent, not gaping when closed, a proximal tooth on in each cutting edges, and series of denticles on each base of finger.

Size. The largest male TL 78.8 mm, CL 17.8 mm; the largest female TL 88.8 mm, CL 16.7mm; 103 ovigerous females were examined, TL 35.8 to 88.8 mm, CL 7.6 to 16.7 mm, with small and numerous eggs.

Remarks

This species is most similar to Macrobrachium panamense Rathbun, 1912. The two can be distinguished by differences in the rostrum. The rostrum in M. amazonicum is low and strongly convex on the orbital region; in contrast, it is high and slightly convex on the orbital region in M. panamense. In some females and immature males, the chelae of the second pair of pereopods have the same carpus length and the internal pair of espinules is overreaching the telson’s midpoint.