Abstract A new species of Knodus from the Mearim and Munim River basins, Northeastern Brazil, is herein described based on integrative taxonomy, by using different molecular based species delimitation methods and independent approaches. The new species possesses the combination of character states that usually diagnoses the genus. The new species possesses a similar colour pattern to K. victoriae, which is also morphologically similar to it. The species described herein differs from K. victoriae by possessing more total vertebrae, more branched anal-fin rays, and fewer circumpeduncular scales. We also provide a detailed discussion of the morphological diagnostic features exhibited by Knodus species from adjacent river basins.