A New Species of Hemigrammus from the Lower Amazon Floodplain (Characiformes: Characidae)

Abstract

Abstract Hemigrammus diagonicus, new species, is described from the lower Amazon River floodplain, near Juruti, State of Para, Brazil. The new species shares with H. silimoni the presence of a dark blotch on the dorsal lobe of the caudal fin, absent in all other species of the genus. It is distinguished from H. silimoni by the autapomorphic presence of the caudal-fin blotch shaped like a bar that extends diagonally from the base of the median rays to the end of the upper lobe rays. Hemigrammus diagonicus, new species, is further distinguished from H. silimoni by a combination of meristic and morphometric characters, such as length of anal-fin base and horizontal eye diameter. Comments on the color patterns displayed by the species of Hemigrammus are presented. Hemigrammus diagonicus, nova especie, e descrita da varzea do baixo Rio Amazonas, proximo a Juruti, Para, Brasil. A nova especie compartilha com H. silimoni a presenca de uma mancha escura no lobo dorsal da nadadeira caudal, ausente em todas as dema...