Contribution to the knowledge of Tonatia bidens (Chiroptera: Phyllostomidae) at its southernmost distribution range: new records, echolocation calls and genetic evidence from Argentina

The greater round-eared bat, Tonatia bidens , is among the least-documented phyllostomids in Argentina, lacking published records for more than two decades. Here, we provide the first integrative evidence of its persistence at the southernmost edge of its range, within the Yabotí Biosphere Reserve, Misiones. We document two newly recorded individuals whose systematic identity was supported by external morphology and mitochondrial cytochrome b sequencing ( Cyt b ). We also present the first description of the species’ echolocation calls in the country, characterized by a multi-harmonic structure with peak energy concentrated in the third harmonic. Mitochondrial analyses based on the complete Cyt b revealed two distinct and private haplotypes, and phylogenetic reconstruction placed the Argentine samples within a well-supported T. bidens clade. Mean pairwise genetic distances showed marked divergence from T. maresi (16.1 %) and T. bakeri (15.0 %), consistent with interspecific differentiation within the genus. Together, these results confirm the continued presence of the species in the Atlantic Forest of Argentina and underscore the evolutionary relevance of peripheral populations for maintaining genetic diversity within the genus.