Tuesday, July 5, 2016

[Ichthyology • 2014] Moenkhausia rubra • A New Species of Moenkhausia (Characiformes: Characidae) from rio Juruena, upper rio Tapajós basin, Brazil


Moenkhausia rubra 
Pastana & Dagosta, 2014


ABSTRACT

Moenkhausia rubra, new species, is described from the upper rio Juruena, rio Tapajós basin, Mato Grosso, Brazil. The new species is distinguished from its congeners, except M. hemigrammoides and M. nigromarginata, by the dark pigmentation on the anteriormost rays of both dorsal and anal fins. Moenkhausia rubra is distinguished from the aforementioned species by the number of branched anal-fin rays 17-20 (vs. 20-25), presence of a dark blotch on the caudal peduncle extending to middle caudal-fin rays, absence of longitudinal black zigzag stripes between longitudinal rows of scales on body, and other details of coloration.

Key words: Amazon; Moenkhausia nigromarginata; Neotropical fishes; Ostariophysi; Tetra




Diagnosis. Moenkhausia rubra is distinguished from all congeners, except M. hemigrammoides Géry and M. nigromarginata Costa, by the presence of dark pigmentation on the anteriormost rays of dorsal and anal fins. It can be distinguished from M. hemigrammoides and M. nigromarginata by the number of branched anal-fin rays 17-20 (vs. 20-22 in M. nigromarginata and 22-25 in M. hemigrammoides). It can be further distinguished from M. hemigrammoides by the presence of a dark blotch on the caudal peduncle extending to middle caudal-fin rays (vs. absence) and from M. nigromarginata by the absence of dark pigmentation on the anteriormost pelvic fin rays (vs.dark pigmentation present), absence of dark pigmentation along the distal margin of anal fin (vs. presence) and absence of longitudinal black zigzag stripes between longitudinal rows of scales on body (vs. presence). Moenkhausia rubra can also be distinguished from its congeners by the combination of the following characters: 5 or 6 scale rows above and 4 or 5 scale rows below the lateral line, 17-20 branched anal-fin rays, 33-34 lateral line scales, 3-6 maxillary teeth, one round humeral spot, absence of reticulated color pattern on body, absence of a dark broad stripe extending from the opercle to the caudal peduncle, distal portion of caudal-fin lobes hyaline, and dark caudal-peduncle spot extending posterior to the middle caudal-fin rays.

Etymology. From the latin ruber (red), in allusion to the reddish coloration of the body, and the dorsal, adipose, and caudal fins in live specimens. An adjective.

Distribution. Moenkhausia rubra is known from rio Juína and rio Juruena, rio Juruena basin, upper rio Tapajós drainage, Mato Grosso State, Brazil.

Fig. 6. Live specimens of: (a) Moenkhausia aurantia, MZUSP 113835, 48.3 mm SL, Brazil, Goiás, rio Tocantins basin; (b) Moenkhausia nigromarginata, MZUEL 8009, 50.0 mm SL, Brazil, Mato Grosso, rio Tapajós basin. 

Murilo N. L. Pastana and Fernando C. P. Dagosta. 2014. Moenkhausia rubra, A New Species from rio Juruena, upper rio Tapajós basin, Brazil (Characiformes: Characidae). Neotrop. ichthyol. 12(2). DOI:  10.1590/1982-0224-20130183

RESUMO: Moenkhausia rubra, espécie nova, é descrita do alto rio Juruena, bacia do rio Tapajós, Mato Grosso, Brasil. A espécie nova diferencia-se de todos os congêneres, exceto M. hemigrammoides M. nigromarginata, pela presença de pigmentação escura nos raios mais anteriores das nadadeiras dorsal e anal. Moenkhausia rubra distingui-se das espécies acima mencionadas pelo número de raios ramificados na nadadeira anal 17-20 (vs. 20-25), presença de uma mancha escura no pedúnculo caudal se estendendo até os raios medianos da nadadeira caudal, ausência de faixas em zigue-zague longitudinais entre as séries longitudinais de escamas no corpo, além de outros detalhes de coloração.

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