Pseudacanthicus nyktos is a recently described loricariid catfish previously considered restricted to the lower Xingu River basin in the eastern Brazilian Amazon. Herein, we report new records from the Turiaçu River basin, Maranhão State, northeastern Brazil, supported by morphological and molecular evidence. Additional records were obtained through the reanalysis of COI sequences available in public databases and the examinat...

Accurate species identification is a challenge in megadiverse regions, where morphology alone can lead to overestimation or underestimation of biodiversity. In this context, the incorporation of molecular approaches, such as DNA barcoding, has been useful in accurately estimating regional biodiversity, revealing cryptic diversity, and enabling identification by non-specialists. This study generated a molecular database of fish...