Substantial Neotropical bat diversity likely remains undescribed and vulnerable to extinction

Abstract Numerous undescribed species face extinction before formal scientific recognition. Despite research advances, the exceptional bat diversity of the Neotropics remains overlooked, with accelerating habitat loss threatening unrecognized lineages with silent extinction, requiring urgent conservation prioritization. Here, we integrate molecular species delimitation, phylogenetic inference, ecological niche modelling, and spatial conservation analyses to identify 95 Neotropical bat lineages that may represent undescribed species within 45 complexes, revealing that at least one-fifth of the recognized taxa may harbor hidden diversity spanning the entire evolutionary spectrum. This overlooked diversity faces a countdown to extinction: 62% of complexes face imminent habitat loss, and most are projected to lose over 50% of their suitable habitat by 2070. At current description rates, formally recognizing this diversity would take decades, a timeframe these putative species cannot afford. We develop a Hidden Species Richness (HSR) Index that pinpoints ten hidden diversity hotspots where undescribed richness coincides with significant human threats and extreme climate vulnerability. These hotspots highlight regions where research efforts are most needed, transforming crises into priorities. This race against extinction requires immediate taxonomic attention to document this biodiversity before it vanishes.