Updated checklist of freshwater Decapoda (Brachyura and Caridea) from the Parnaíba river basin, northeastern Brazil, with a new record for the watershed

Our work provides a checklist of freshwater decapods (Brachyura and Caridea) from the Parnaíba river basin, Brazil, based on field collections carried out between 2018 and 2020. Eight species were collected at 30 sampling sites in the main river channels, streams, and ponds throughout the upper, middle, and lower regions of the Parnaíba river basin. The species of shrimp reported herein are <em>Atya gabonensis</em> (Gibiel, 1875) (Atyidae), <em>Macrobrachium amazonicum </em>(Heller, 1862), <em>Macrobrachium brasiliense </em>(Heller, 1862), <em>Macrobrachium jelskii </em>(Miers, 1778), and <em>Macrobrachium olfersii </em>(Wiegmann, 1836) (Palaemonidae), while crab species reported are <em>Goyazana castelnaui </em>(H. Milne-Edwards, 1853), <em>Sylviocarcinus pictus </em>(H. Milne-Edwards, 1853) (Trichodactylidae), and <em>Kingsleya parnaiba </em>Pralon, Pinheiro & Santana, 2020 (Pseudothelphusidae). The record of <em>Macrobrachium brasiliense</em> is the first for the Parnaíba river basin. The knowledge of the diversity of freshwater decapod fauna can contribute to the conservation of species and their habitats.