Predicting the South American invasion pathways of the mayfly Cloeon dipterum Linnaeus 1761 (Ephemeroptera: Baetidae) using species distribution models

Abstract Cloeon dipterum is one of the rare exotic aquatic insect species found in the American continent. The species was recently introduced to Argentina. Apart from a few recent records concentrated in a small area in Argentina, there are no data available on its distribution on the continent. Using modelling techniques, we predicted for the first time the current and future areas of high invasion risk in South America. We produced species distribution models (SDMs) using six algorithms and based on 4672 occurrences and 20 environmental variables for both current conditions and future scenarios (GCMs: CanESM5 and MIROC6/SSPs: 2‐4.5 and 5‐8.5). The models predicted two large contiguous areas of high suitability and stability over time in all future forecasts (Paraná and coastal pathways), both of which are connected to the colonised area in Argentina and extend to Paraguay, Uruguay, and Brazil. The models also identified two potential new areas for introduction, Patagonia (Chile and Argentina) and the northeast of Brazil. However, introduction is considered unlikely in the highly suitable area in the Brazilian Northeast due to the lack of connectivity with donor areas. Models provide specific regions that can be used to detect colonisation expansion and improve our ability to implement measures to prevent introduction. Our results provide evidence that C. dipterum will be a long‐term element of South American diversity. Its persistence in distinctive climatic scenarios may pose a threat to resident controphic species, such as Callibaetis .