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.
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Thanks are due to Richard P. Vari (in memorian, USNM), Aléssio Datovo da Silva (MZUSP), Mark Weastnet and Kevin Swagel (FMNH), John Lundberg and Mark Sabaj-Pérez (ANSP) and Paulo C. Venere (UFMT) for loan of specimens. We are especially in debt to Karsten Hartel and Andrew D. Williston (MCZ) for an extended loan of specimens to JCG that included the types of Schizodon fasciatus, S. dissimilis, and S. vittatus, as well as sending photos of the Porto de Moz specimens, identified by Garman (1890) and Borodin (1931) as S. vittatus. We also thank Handerson Batista, Edson Santana, and Nick Narezzi, who helped collect specimens of the new species in the field. Special thanks to Oscar A. Shibatta (MZUEL) who helped with the sheared principal component analysis; to Paulo H. F. Lucinda (UFT), who provided valuable information about the Castelnau collection localities in the Amazon basin; and to Leandro Sousa for sending us pictures of live specimens and data on LIA specimens. Brian Sidlauskas (OSU) and an anonymous referee provided useful suggestions. Our gratitude is also to Camila F. Perez (LISDEBE-UFSCar) to help with map, photos, and collection management. This study was partially supported by Fapesp (process 2018/04388–7). Authors were funded by CNPq (processes 302872/2018-3, 303524/2019-7).
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- Identification key