Biodiversity hotspots of recent freshwater Ostracoda in Brazil

Brazil occupies almost half of the surface area of South America and covers different climatic zones, which leads to great ecological diversifications, forming distinct biogeographical areas or biomes. This reflects the megadiversity of Brazilian flora and fauna, including the high level of endemism. A literature review in 1994 recorded 260 species in 53 genera of recent non-marine ostracods from the South America (MARTENS & BEHEN, 1994). Of these, 91 species in 32 genera occurred in Brazil according to a 1998 checklist (MARTENS et al., 1998). Here, we present the results of recent inventories of freshwater ostracods from Brazil, including an overview of the geographical distribution of species. The expeditions of the PELD (Long-term Ecological Research Program in the Upper Paraná River Floodplain) and SISBIOTA (National Biodiversity Research System program - carried out in four Brazilian floodplains), increased these numbers to 133 species in 41 genera, including the descriptions of 31 new species in nine new genera (e.g. FERREIRA et al., 2020; ALMEIDA et al., 2023). The highest richness of ostracods has been found in the Atlantic Forest biome, which includes the upper Paraná River floodplain. The Amazon biome, where the Amazon floodplain is located, had the lowest diversity of ostracods but has also received much less attention in recent decades: the upper Paraná River floodplain has almost continuously been monitored since 2004, while only two (2011 and 2012), relatively short, collecting trips have been made in the Amazon floodplain. Thus, these results emphasize the relevance of long-term biodiversity monitoring studies. In addition, our results show that there is still little knowledge about the biodiversity of Brazilian ostracods, given that extensive areas remain unexplored.

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