Exploring Biodiversity Hotspots in Argentina: Contributions and New Reports on the Freshwater Ostracods (Ostracoda—Crustacea)

Subtropical wetlands are considered biodiversity hotspots due to their complex and diverse habitats; however, their ostracod communities remain underexplored, particularly in the Northeastern Argentina (NEA) region. This study presents the first regional survey that combined previously published literature with field sampling of ostracod communities. Five families and 30 ostracod species were identified from 28 wetlands across the NEA region, including water bodies with different anthropogenic influences, plant compositions and water regimes, such as temporary and permanent lakes, streams and paddy fields. Seventeen out of the 30 species were recorded for the first time in Argentina, and a further two are new records for the region, increasing to 84 species the ostracod fauna reported for the country. Some taxa are left in open nomenclature, highlighting the need for further taxonomic research, species identification and broader field sampling to fully understand the diversity and ecological roles of these invertebrates. This study provides a valuable baseline for future studies contributing to wetlands conservation efforts and sustainable management in this biodiverse but vulnerable region.