Resolving the taxonomic status of Abrothrix andina (Rodentia, Cricetidae): evidence from topotypic specimens

Recent studies have demonstrated that the Andean sigmodontine rodent Abrothrix andina (Sigmodontinae, Abrotrichini) is neither widespread nor a senior synonym of several nominal taxa (i.e., dolichonyx, cinnamomea, jucundus, gossei, and polius) described from Argentina, Chile, and Peru since the 19th century. However, a comprehensive taxonomic and nomenclatural reassessment requires the examination of type material. Here, we address this by analyzing topotypic specimens collected from three Andean localities near Santiago de Chile (Chile), the type locality of A. andina. Cytochrome b sequences from these specimens cluster within Abrothrix olivacea. These results support treating Abrothrix andina (Philippi in Philippi & Landbeck, 1858) as a junior synonym of Abrothrix olivacea (Waterhouse, 1837). Additionally, the nominal form Abrothrix gossei (Thomas, 1920) warrants recognition as a distinct species of Abrothrix, sister to A. olivacea. Although this study appears to complete the taxonomic reassessment of A. andina, a remote possibility remains that its holotype, currently lost, represents a still-unsampled Andean highland population, now extinct or extremely rare due to climate change.