Range‐Wide Molecular Systematics of Mastiff Bats Reveals Heterogeneous Lineage Differentiation and Two Unrecognised Lineages in the Neotropics

ABSTRACT The genus Molossus is one of the most taxonomically challenging groups of Neotropical bats because of the marked morphological similarity among species, uneven geographic sampling, and conflicting signals across molecular markers. We conducted a comprehensive range‐wide molecular systematic assessment of the genus, integrating four mitochondrial and two nuclear markers. By combining curated data with new sequences from underrepresented regions in Argentina, Paraguay, and Peru, we evaluated lineage distinctiveness using phylogenetic, phylogeographic, and species delimitation methods. Our results reveal a marked heterogeneity in evolutionary boundaries within Molossus . While several species were recovered as well‐defined lineages, others exhibited low divergence and poorly resolved limits, challenging current nominal classifications. Notably, we identified two previously unrecognised lineages in the Paraguayan Humid Chaco and Peruvian Amazonia, suggesting the existence of undescribed species. This study provides an expanded genetic framework for Molossus across its full distribution. Our findings demonstrate that lineage boundaries are highly heterogeneous and highlight how expanding geographic coverage, particularly in the southern Neotropics, is essential to uncovering hidden biodiversity. These results offer a robust foundation for future integrative taxonomic revisions and emphasise the critical value of sampling historically overlooked regions to resolve complex evolutionary histories in Neotropical fauna.