A new species of Tetragonopterus tetra from the Amazon River drainage has been described in the latest issue of the journal Neotropical Ichthyology.
Naming the new tetra Tetragonopterus carvalhoi after Brazilian ichthyologist Marcelo de Carvalho, Bruno Melo and coauthors distinguish it from congeners by the lozenge-shaped spot on the caudal peduncle, extending from the level of the adipose fin to the middle caudal-fin rays (congeners have a round to square-shaped spot confined to the rear half of caudal peduncle).
It further differs from some congeners in having 6–10 predorsal scales and lacking dark stripes on the sides of the body.
In addition to the morphological characters, the authors also found the new species to be genetically distinct from congeners in the partial sequence of the mitochondrial cytochrome oxidase C subunit I gene that was analysed.
For more information, see the paper: Melo, BF, RC Benine, TC Mariguela and C Oliveira (2011) A new species of Tetragonopterus Cuvier, 1816 (Characiformes: Characidae: Tetragonopterinae) from the rio Jari, Amapá, northern Brazil. Neotropical Ichthyology 9, pp. 49–56.