New perspectives on the phylogeography of Aylacostoma Spix, 1827 (Gastropoda: Hemisinidae) from the Paraná river basin

Context. Aylacostoma species (Gastropoda, Hemisinidae) are sensitive to environmental changes and low dissolved oxygen levels, making them particularly vulnerable to disturbances such as dam construction. The "Aylacostoma Project" aims to conserve some species of the genus, maintaining populations in captivity. Phylogeographic studies play a key role in this context, as they provide insights into the genetic diversity of populations, an essential aspect for conservation. Aims. The main objective of this study was to investigate the phylogeographic structure and genetic diversity of three Aylacostoma species from the Paraná river basin: A. brunneum, Aylacostoma sp., and A. chloroticum. Methods. The analyses were based on 81 partial sequences of the mitochondrial COI region from different localities, obtained from GenBank and the present study. Key results. Eight haplotypes were identified across the analyzed populations, with six haplotypes comprising A. chloroticum. Some haplotypes were exclusive to specific localities. Conclusion. This study highlights new information about the phylogeographic pattern of the group, revealing a phylogeographic structure among Aylacostoma species from the Paraná river basin. Implications. This is the first phylogeographic study of Aylacostoma to include molecular data from natural populations of A. chloroticum and Aylacostoma sp. from the upper Paraná river basin, Brazil.