Integrative taxonomy of the black-barred disk pacus (Characiformes: Serrasalmidae), including the redescription of Myloplus schomburgkii and the description of two new species

Presently, Myloplus schomburgkii is the most easily recognized species among the serrasalmids by having a vertical black bar in the middle of the body. However, through a broad taxonomic review, including DNA barcoding and morphological analyses, we were able to identify and describe two new species that also share a dark vertical bar on the flank. In addition, we redescribe M. schomburgkii, designating a neotype and restricting the type-locality to rio Negro in Barcelos, Amazonas State, Brazil. The three lineages of black-barred pacus present high molecular divergences (7.9–11%) and can be distinguished by differences in the shape of the vertical bar, shape of females’ anal fin, number of total vertebrae, number of total branched dorsal-fin rays, among other characters. Although the existence of these two new species has been hidden due to many morphological similarities, mainly the presence of the black bar, the three lineages do not compose a monophyletic group, with one of the new species being recovered as sister to Ossubtus xinguense. This result reinforces the necessity of the redefinition of the Myleini genera.