A new species of Characidium (Characiformes: Crenuchidae) from the Iguaçu National Park, Rio Iguaçu basin, Paraná, Brazil

Researchers have identified a new species of Characidium fish within the Iguaçu National Park, Brazil. This discovery was supported by both morphological and molecular analyses, including multiple species delimitation methods, which confirmed its distinctiveness from known congeners. The new species is characterized by the absence of vertical bars or spots along its body, a scaled isthmus and adipose fin, scales below the lateral line, and a thin dark midlateral stripe. While it shares a reticulated color pattern with C. xanthopterum, genetic distance analysis revealed only 4.2% divergence, indicating it is a distinct species. Phylogenetic studies further showed that this new species is closely related to C. itarare from the Paranapanema river basin. Despite being found within a protected area, its limited distribution to just two creeks raises significant concerns for its long-term conservation.

Stabile, B. H. M., dos Reis, R. B., de Oliveira, A. V., & da Graça, W. J. (2025). A new species of Characidium (Characiformes: Crenuchidae) from the Iguaçu National Park, Rio Iguaçu basin, Paraná, Brazil. Journal of Fish Biology, 107(2), 454–465. Portico. https://doi.org/10.1111/jfb.70035