Ctenomys roigi

This lineage corresponds to the species firstly described by Contreras (1988) who pointed out its morphological distinctiveness. This species is distributed in an extremely limited area, within less than 100 km 2, and thus was considered as Critically Endangered in the IUCN Red List of Threatened Species (Bidau et al. 2008a). To date, three nearby populations have been ascribed to Ctenomys roigi: Arroyo Pehuajó, Costa Mansión and Estancia San Luis, located in the northwest extreme of the Corrientes Province (Figure 2). All three populations share a distinctive karyotype, 2n = 48 FN = 80, with a unique FN in the Corrientes group (Ortells et al. 1990, Table 1). Ctenomys roigi is also a well supported lineage in terms of genetic exclusivity, since it forms a unique SSR cluster and also results monophyletic in the mtDNA phylogeny (Table 1, Figure 3).