Reassessment of recent mammal extinctions in Argentina: Evidence of overlooked regional and global losses

Several Argentine mammals were last recorded more than half a century ago. This could mean that more sampling efforts are needed, that they are possible synonyms of other extant taxa, or that they have gone extinct (locally or globally). We reviewed literature on the 372 native continental mammal species from Argentina to identify those lacking recent observations (<50 years), assessing year and context of the last record, considering possible causes for the absence of recent data, and concluding with a distinction between those that can be assumed as extant and those that are most likely extinct. After identifying 20 species (one didelphimorph marsupial, one sloth, one bat, 14 rodents and three carnivores), we ruled out extinction for eight: seven come from undersampled areas and/or have habits that tend to elude sampling (thus, they may still be extant and more fieldwork could lead to their rediscovery), three would be cases of synonymy, and probable new specimens were recently collected for two. For the remaining 12 species, we found sufficient information, such as habitat destruction and failed sampling efforts, to believe they have gone extinct: five regionally for Argentina (although one’s type locality is uncertain, meaning it may have never dwelled in this country) and seven globally. Among them, all small mammals are listed as extant by the IUCN. Our assessment proposes a significant increase in the number of regional and global extinctions, while highlighting the need of increasing sampling efforts and the importance of museum collections to determine species’ current status.