Acrostichum Danaeifolium (Pteridaceae) From Argentina And Paraguay: Rio Pilcomayo National Park (Formosa, Argentina) As A Conservation Area Of The Species In The Eastern Chaco Oriental

Background and aims: Acrostichum danaeifolium is a widely distributed species in the Neotropics, growing in freshwater or saltwater habitats. In Argentina and Paraguay are scarce records cited by previous papers. The objective of this work is to study A. danaeifolium for Argentina and Paraguay, emphasizing the review of its distribution and the history of the botanical collections of the species.M&M: Specimens deposited in national and international herbaria and collected during monitoring tasks in the Rio Pilcomayo National Park (Formosa, Argentina) were studied. Also, records were consulted in the GBIF and iNaturalist databases. The analysis of the diagnostic characters was carried out under a stereoscopic magnifying glass.Results and Conclusions: The diagnostic characters of A. danaeifolium are illustrated, and a map of the species distribution in Argentina and Paraguay is provided. We corroborate that the A. danaeifolium populations registered to date for both countries are scarce and are restricted to the Chaco Oriental district, where they grow associated with floodplains such as river banks and freshwater lagoons. The specimens found in the Rio Pilcomayo National Park represent the first record of the species in a protected area, the first record in Formosa province, the most boreal record of Argentina and the first collection in the country in 70 years. Due to the intense deforestation recorded in the Chaco Oriental district in recent decades, the RPNP takes on special relevance for the conservation of the species.