Integrative taxonomy reveals two new species of whiptail catfishes Loricaria (Siluriformes: Loricariidae) from northeastern Brazil

Abstract

Two new species of whiptail catfish, Loricaria (Siluriformes: Loricariidae), were discovered in the Munim and Itapecuru river basins, Maranhão State, northeastern Brazil, through an integrative taxonomic approach combining morphology and mitochondrial DNA. Linear discriminant analysis revealed three morphometrically distinct groups, and coxI ‐based phylogeny identified four genetically divergent lineages of Loricaria in northeastern Brazil. The new species are clearly distinguished from their closest congeners, L. turi and L. parnahybae , by unique diagnostic traits, including abdominal plate patterns, pectoral girdle coverage and the shape of the postorbital notch. Genetic divergences among lineages, estimated as mean interspecific K2P distance, ranged from 2.2% to 4.1%, similar thresholds commonly applied for species delimitation in Loricariidae. Both species exhibit restricted distributions and are endemic to river basins under increasing anthropogenic pressure. These results underscore the underestimated diversity of Loricaria in northeastern Brazil and reinforce the role of coastal drainages as areas of endemism and speciation.

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