Description of a new species of Astyanax (Characiformes: Characidae) from the Rio Xingu basin, Pará, Brazil

Abstract

A new species of Astyanax is described from the upper Rio Iriri, rio Xingu basin. The new species can be distinguished from all congeners by a unique combination of characters, including color pattern (i.e. presence of a dark longitudinal stripe with relatively constant width along the body, two vertically elongated diffuse humeral spots, concentration of dark pigments on the anterior portion of scales in the abdominal region), 40–43 lateral line scales, 1–2 pentacuspid maxillary teeth. Astyanax sp. n.presents sexual dimorphism, with males differing from females by having bony hooks on the anal fin rays. The description of another endemic species of Characidae in the southern Amazon reinforces that the region harbors a ichthyofaunistic diversity, while at the same time, it is still taxonomically poorly understood.