Macrobrachium amazonicum (Heller, 1862)

Santos, Maria Aparecida Laurindo dos, Castro, Patrícia Madedo de & Magalhães, Célio, 2018, Freshwater shrimps (Crustacea, Decapoda, Caridea, Dendrobranchiata) from Roraima, Brazil: species composition, distribution, and new records, Check List (Washington, D. C.: 1974) 14 (1), pp. 21-35 : 24-26

Macrobrachium amazonicum (Heller, 1862) ( Figs 3A–C, 8)

Previous records. Pileggi et al. (2013).

Identification characters ( Fig. 3A–C). Rostrum long, slender, sinuous, crested over the eyes, distal portion curved upwards, distinctly reaching beyond scaphocerite; rostral formula: 6–12(1 post-orbital tooth)/8–11. Carapace with antennal and hepatic teeth present, otherwise smooth; abdomen smooth, pleura of second somite enlarged and overlapping pleuron of first and third somites. Telson tapering, distally without distinct posterior margin, with 2 pair of posterolateral spines, inner pair distinctly larger than outer one, not overreaching (in adults) tip of telson.

Material examined. 6 males, 7 females (1 ovig.) ( INPA 2341), Normandia, lago Caracaranã, [03°50ʹ50.934ʺ N, 059°46ʹ44.471ʺ W], tributary of rio Tacutu, 27-III-1992, colls. J. A.A. Gomes and J.S. Zuanon; 2 males, 1 ovig. female ( INPA 2397), Amajarí, Maracá Ecological Station, igarapé Grande, rio Uraricoera, [03°27ʹ N, 061°41ʹ W], 24-III-2008, coll. unknown; 4 males ( INPA 2321), Bonfim, igarapé Arraia, BR 174 road, 03°21’05ʺ N, 059°54’12ʺ W, tributary of rio Tacutu, 25-XI-1996, colls. V. Py-Daniel et al.; 1 male ( INPA 2337), Bonfim, igarapé Surrão, [02°51ʹ17.403ʺ N, 060°33ʹ8.070ʺ W], tributary of rio Branco, 29-X-1987, colls. V. Py-Daniel et al.; 2 males ( INPA 2338), Cantá, unnamed igarapé on BR 401 road, [02°47ʹ36.589ʺ N, 060°38ʹ26.33ʺ W], tributary of rio Branco, 25-III-1992, colls. J.A.A. Gomes, J. Zuanon, I. Sullivan and J. Albert; 4 males, 5 females ( INPA 2340), Alto Alegre, igarapé Tupaquiri, [02°58ʹ56.893ʺ N, 061°19ʹ26.59ʺ W], tributary of rio Uraricoera, 24-X- 1997, colls. V. Py-Daniel et al.; 9 spec. (2 ovig. females) ( INPA 2379), Cantá, Vicinal I, fazenda Laçador, in a dammed stream, tributary of rio Branco, 02°07ʹ18.3ʺ N, 060°50ʹ57.5ʺ W, 25-V-2014, colls. M.G.S. Silva and F.P.L. Santos; 18 spec. ( MIRR 317), Mucajai [02°26ʹ57ʺ N, 060°55ʹ16ʺ W], Apiaú region, vicinal 1, fazenda Cruvi- ana, igarapé Arraia, tributary of rio Mucajai, 29-III-2010, colls. D.A. Lima and A.S. Sales; 1 ovig. female ( INPA 2369), Caroebe, Entre Rios, rio Jatapú, 00°45ʹ37.1ʺ N, 059°17ʹ08.2ʺ W, 02-II-2015, colls. M.A.L. Santos, F.C. Zanetti, I. R.S. Almeida and S.C. Emídio.

Distribution. Venezuela, Colombia, Guyana, French Guiana, Brazil (Amazonas, Amapá, Acre, Ceará, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará, Pernambuco, Piauí, Rio Grande do Norte, Rio Grande do Sul, Roraima), Peru, Bolivia, Equador, Argentina, Paraguay (see Pimentel and Magalhães 2014 for references; present study). The distribution in Roraima is depicted in Figure 8.

Remarks. The morphology of our specimens agrees quite well with the description provided by Holthuis (1952, 1966), García-Dávila and Magalhães (2003), and Melo (2003). In juveniles the inner pair of posterolateral spines can exceed the tip of telson, which still shows a rather distinct posterior margin.

Pileggi et al. (2013) listed this species from the municipality of Caracaraí, in the lower rio Branco region. The records presented here extend its distribution northwards as far as the rio Tacutu basin, in the northeastern part of the rio Branco basin ( Fig. 8). The species also occurs in the rio Jatapu, a tributary of the rio Uatumã basin.