More on the distribution of cladoceran species: gaps and perspectives in Rio de Janeiro State, southeastern Brazil

Abstract

Our knowledge of cladoceran species composition and distribution of Neotropical taxa is incomplete, therefore misleading the basic understanding of biodiversity processes and biogeographical patterns of this ecologically relevant group. We present new records and an updated checklist of the cladocerans of Rio de Janeiro State (Brazil) based on a critical review of their known distribution throughout the different freshwater ecoregions. Nine marine species were recorded, and 80 non-marine cladocerans were counted from two of the four ecoregions of Rio de Janeiro State. We estimate species richness applying the interpolation and extrapolation method, using iNEXT function. With this approach we compute diversity estimates for rarefied and extrapolated samples up to double the reference sample size (number of studies). Four new records of rare species were included from surveys in the Paraiba do Sul ecoregion. The Fluminense ecoregion shows a higher richness with a more asymptotic curve and thus a lower expected richness in comparison to the Paraiba do Sul ecoregion. Ceriodaphnia cornuta Sars, 1886 was the most frequently found species whilst Moina macrocopa Straus, 1820 was the only non-native species encountered. Our study can contribute to developing a biogeographical understanding of this diverse group in a heterogeneous territory in terms of inland waters. Future studies are suggested to prioritize novel ecoregions and unexplored habitats e.g. littoral zones with high macrophyte and periphyton coverage, brackish waters, saline and high-altitude lakes, as more diverse and heterogeneous habitats will undoubtedly reveal additional records.