Stuck between rivers: a new species of Ctenomys from northern Argentine Patagonia

Ctenomys (tuco-tucos) is one of the most speciose genera of mammals, with around 70 described species. Recently, the rate of new species descriptions within the genus Ctenomys has notably increased, primarily due to recent taxonomic revisions and surveys in previously unexplored geographic areas. In this study, utilizing both morphological and molecular evidence, we describe a new species of Ctenomys from northern Argentine Patagonia, confined between the Colorado and Negro rivers. This new species is a member of the Magellanicus group displaying close relationships with other species distributed in northern Patagonia and adjacent regions (C. bidaui, C. miguelchristie, C. pontifex, and C. pulcer). The major rivers in the region (Colorado and Negro rivers) appear to delineate the distributional boundaries of the identified taxa. We therefore propose that rivers, acting as natural barriers to dispersal, have significantly influenced the diversity of Ctenomys in northern extra-Andean Patagonia.