Integrative taxonomy reveals a new species of Neotropical headstanding fish in genus Schizodon (Characiformes: Anostomidae)

Abstract

Schizodon encompasses approximately 15 species of Neotropical headstanding fishes. Integrative taxonomy, combining molecular and morphometric analyses with traditional taxonomic methods, was used to investigate Schizodon vittatus and its potential new sister species. Molecular differences between the two species in the barcode are greater than intra-specific variation recovered in species of Schizodon, and the two species represent distinct lineages for approximately one million years. The two species are morphologically very similar, and the meristic data showed great overlap. Morphometric analyses also showed overlap among the putative species but indicated differences in caudal-peduncle depth, orbital diameter, and length of anal-fin rays. Color pattern seems to provide a clear diagnostic feature for the two species. Schizodon vittatus usually has four dark brown transversal bars on body, and its sister species has three conspicuous bars, with the fourth, if present, inconspicuous and dorsal to the lateral line. Schizodon vittatus is redescribed based on the type and recently collected specimens, its type locality is revisited, and its known distribution restricted to the Araguaia and Tocantins drainages. The new species, sister to S. vittatus, distributed in the Xingu and Tapajós drainages, is described. A key for the identification of the Amazon clade species of Schizodon is provided.

Evaluation of ichthyofauna in lotic and lentic environments in the Araguaia River basin, Cerrado Biome, Brazil

“…As with the Cichlidae family, studies that unravel the gaps in the classification and distribution of species in the Anostomidae family deserve attention. Ferreira, Oliveira, Venere, Galetti Jr., and Martins (2007), Olivatti et al (2011) and Garavello et al (2021) investigated genetic characters of genera from this family. Garavello and Santos (2009) found a species identified as Leporinus unitaeniatus and stated that there is a shortage of taxonomic information about the specimens of the genus Leporinus for the Tocantins/Araguaia basin.…”