Ancient DNA reveals the identity and geographic origin of the syntype of <i>Ctenomys brasiliensis</i> , the type species of the genus <i>Ctenomys</i>

Abstract Ctenomys de Blainville 1826 ranks among the 10 most species-rich extant mammal genera. However, the taxonomic history of Ctenomys brasiliensis de Blainville 1826—the type species of the genus—has long been obscured by limited information on the collection data of its type material, further complicated by an uncertain geographic origin. In this study, we employed ancient DNA techniques to sequence the complete mitogenome of the extant syntype specimen and conducted an extensive historical investigation to reconcile the original locality names with current geographic designations in South America. Our results unequivocally demonstrate that the type specimen corresponds to the species currently recognized as Ctenomys minutus Nehring 1887. This finding resolves a century-old controversy regarding the provenance of the C. brasiliensis syntype, refuting previous hypotheses that proposed southeastern Brazil or Uruguay as its collection site. Instead, evidence points to a third, previously overlooked location in southernmost Brazil. Earlier studies failed to identify this location due to confusion arising from outdated geographic nomenclature and labeling inaccuracies—issues addressed here through an integrative mitogenomic and historical approach. Complementary quantitative morphological analyses reinforce these conclusions, revealing a close affinity between C. brasiliensis and C. minutus within the same species group. Accordingly, we validate C. brasiliensis and propose C. minutus as its junior synonym. Our study highlights the critical role of robust DNA analyses combined with historical data in clarifying the identity and geographic origin of type specimens, particularly in taxa like Ctenomys, characterized by phenotypic similarity and specimens collected centuries ago. LSID:Version of Record, first published online January 11, 2019, with fixed content and layout in compliance with Art. 8.1.3.2 ICZN.Nomenclature statement - A life science identifier (LSID) number was obtained for this publication: urn:lsid:zoobank.org:pub:6CCE7CD0-2722-4041-9659-1CF50407775D.