Annotated Checklist and Latitudinal Distribution of Freshwater Bivalves from Chile

Freshwater bivalves are a poorly represented but biogeographically informative component of Chilean inland waters. Their distribution offers a useful framework for evaluating latitudinal gradients, historical biogeography, and the southern limits of non-marine molluscs in South America. Here, we present a georeferenced synthesis and annotated checklist of Chilean freshwater bivalves based on 90 occurrence records compiled from the literature and associated datasets. The records comprise 12 species in three genera: Diplodon, Euglesa and Sphaerium, belonging to Hyriidae and Sphaeriidae. Diplodon chilensis was the most frequently recorded species, with 52 records and a latitudinal range from approximately 30.5° S to 46.6° S. By contrast, the southernmost records were represented by sphaeriine clams, especially Euglesa magellanicum from Laguna El Salto, Isla Navarino, at approximately 55.0° S. Other high-latitude records included Euglesa lebruni from Punta Arenas, Sphaerium patagonicum from Puerto Natales and Euglesa chilense from the Aysén Region. The dataset indicates contrasting biogeographical patterns between large-bodied hyriid mussels and small-bodied sphaeriid clams. Whereas Diplodon appears mainly associated with central-southern and Patagonian continental freshwater systems, the sphaeriine clams represented in the dataset extend farther south into Magellanic and sub-Antarctic environments. This contrast may reflect differences in dispersal capacity, ecological tolerance, habitat use and historical responses to Quaternary glaciations. The checklist and distributional synthesis provide a baseline for future taxonomic, phylogeographical and conservation studies of Chilean freshwater bivalves.