Abstract
A new species of the genus Tetragonopterus is described from specimens of the upper and middle portions of the rio Tocantins drainage. The new species can be distinguished from all congeners by the possession of a very uniquely shaped maxilla.
Highlights
The genus Tetragonopterus Cuvier comprises characids distributed throughout the drainages of the río Orinoco, rio Amazonas, rio Tocantins-Araguaia, rio São Francisco, rio Paraná-Paraguay, the coastal drainages of the Guianas, and the Amapá State of Brazil, and the coastal drainages of northeastern and eastern Brazil (Melo et al, 2011; Reis, 2003)
Mirande (2010: 503) hypothesized eight character states as autapormorphic for Tetragonopterus argenteus. These character states were evaluated for T. akamai
1) The laterosensory canal in the sixth infraorbital of T. akamai is tripartite, exhibiting an anterior dorsal portion running towards the neurocranium
Summary
The genus Tetragonopterus Cuvier comprises characids distributed throughout the drainages of the río Orinoco, rio Amazonas, rio Tocantins-Araguaia, rio São Francisco, rio Paraná-Paraguay, the coastal drainages of the Guianas, and the Amapá State of Brazil, and the coastal drainages of northeastern and eastern Brazil (Melo et al, 2011; Reis, 2003). The genus currently comprises seven species considered valid (Silva et al, 2013). Recent ichthyofaunal surveys in the upper and middle portions of the rio Tocantins drainage yielded samples of a new species of Tetragonopterus that we formally describe
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