A new Silver Dollar species of Metynnis Cope, 1878 (Characiformes: Serrasalmidae) from Northwestern Brazil and Southern Venezuela

Rafaela Priscila Ota,Instituto Nacional De Pesquisas Da Amazônia, Brazil ,Lúcia Helena Rapp Py-Daniel,Michel Jégu,Muséum National D'histoire Naturelle, France

doi:10.1590/1982-0224-20160023

Rafaela Priscila Ota, Instituto Nacional De Pesquisas Da Amazônia, Brazil + Show 3 more

Open Access

https://doi.org/10.1590/1982-0224-20160023

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Abstract

ABSTRACT A new Metynnis is described from the rio Negro in Brazil and Venezuela, and from black- or clearwater tributaries in Brazil including the rios Parauari, Uatumã, Trombetas, and Sucunduri (the latter belonging to the rio Madeira basin). The new species can be distinguished readily from all congeners by having a high concentration of dark chromatophores on the lateral line scales. It can be further distinguished by the combination of head length 24.3-27.5% of SL, 13-18 gill-rakers on upper limb and 16-24 gill-rakers on lower limb. The new species is most similar to and likely most closely related to Metynnis hypsauchen . These two species share a similar color pattern, body shape and sexual dimorphism of the anal fin. However, they differ in that M. hypsauchen has a lightly pigmented lateral line. The new species is also distinguished from M. hypsauchen by having 56-65 predorsal scales and 90-104 lateral line scales (vs . 36-54, and 65-82, respectively). A detailed osteological description of the new species is provided.

Highlights

Metynnis Cope, 1878, is one of the most species-rich genera within Serrasalmidae and currently includes 15 valid species
We describe a new species previously reported as Metynnis hypsauchen (Müller & Troschel, 1844), due to similarities in color pattern, body shape and sexual dimorphism of the anal fin
Body measurements are presented as percentages of standard length (SL), except for subunits of the head, which are expressed as percentages of head length (HL)

Summary

Introduction

Metynnis Cope, 1878, is one of the most species-rich genera within Serrasalmidae and currently includes 15 valid species. Zarske & Géry (2008) described M. longipinnis Zarske & Géry, 2008 and M. polystictus Zarske & Géry, 2008 and confirmed M. goeldii Eigenmann, 1903 as a junior synonym of M. lippincottianus (Cope, 1870) In spite of these taxonomic uncertainties, the monophyly of the genus is well accepted and has been corroborated by various authors in both morphological (Machado-Allison, 1982, 1983; Jégu, 2004) and molecular phylogenetic analyses (Ortí et al, 1996, 2008; Calcagnotto et al, 2005; Thompson et al, 2014), with the exception of Cione et al (2009), which recovered a paraphyletic Metynnis. Metynnis cf. hypsauchen Zeinad & Prado, 2012: 153 [Brazil, rio Sucunduri, rio Madeira basin: photo]

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