Figure 1. Geographic distribution and location of extant and fossil specimens analysed in this study: (1) Distribution of extant Zilchogyra species extending down to the Colorado River (striped) in northern Patagonia, distribution of extant Gastrocopta species (dots), the square indicates the fossil record of Gastrocopta from the Pliocene of Mendoza province, the triangle indicates the record of Punctum from Juan Fernández Islands; (2) (inset), detail of the location of Corriguen Aike between Gallegos and Coyle rivers in Santa Cruz province.