The Austrolebias Genus Group (AGG), endemic to the southern portion of the Neotropics, comprises eleven genera of seasonal killifishes, characterized by small body size, restricted geographical ranges, and reliance on ephemeral aquatic habitats. In this study, we performed a comprehensive biogeographic analysis of the AGG, integrating a phylogeny based on 48 taxa that includes 90% of the species in this group with precise distribution data. The main objective was to identify the historical processes—particularly geological and climatic events—that shaped the diversification and current distribution of AGG species. To achieve this, we inferred a time-calibrated phylogeny, reconstructed ancestral area distributions, and analyzed patterns of dispersal and vicariance throughout the group’s evolutionary history. Our results indicate that the AGG began its diversification approximately 13–10 million years ago during the Late Miocene, a period marked by significant geomorphological and climatic changes across the main basins of the La Plata system, including the Paraguay, Paraná, and Uruguay basins, as well as adjacent lowlands. Marine incursions together with tectonic activity and broader paleogeographic changes during this time reconfigured the drainage patterns of major basins, driving dispersal, isolation, and diversification within the group. These findings underscore the pivotal role of paleogeographic and environmental changes in shaping the evolutionary history and current distribution of Neotropical freshwater fishes.
Portelli, S., Serra Alanís, W.S., Krause Lanés, L.E., Montes, M.M., Terán, G.E., Vieira Volcan, M. and Alonso, F. 2026. Historical biogeography of the diverse Neotropical seasonal killifishes of the Austrolebias Genus Group: potential environmental drivers of diversification. Zoologischer Anzeiger 321: 345–358.
 | Guillermo Terán Investigador Adjunto CONICET FML Ictiología |