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.

Resumo: Objetivo Neste estudo, examinamos o efeito do tempo de preservação no comprimento total do corpo e no peso seco de espécimes adultos do cladócero neotropical Ceriodaphnia silvestrii fixados com solução de formalina a 4%. Métodos A relação entre essas variáveis foi examinada sob efeito crescente do tempo (7, 30 e 60 dias) após a preservação usando modelos lineares e análise de variância. Resultados O comprimento corporal total não diferiu estatisticamente entre os cladóceros não-preservados e preservados, enquanto o peso seco foi reduzido com o aumento do tempo de preservação, resultando 15, 47 e 57% de perda de peso, respectivamente. As relações peso-comprimento foram significativamente positivas em todos os tratamentos, embora valores mais elevados tenham sido encontrados em amostras frescas e de 7 dias. Conclusões Destacamos que, para Ceriodaphnia silvestrii, o uso da solução de formalina como método de preservação não é adequado quando o principal interesse é a estimativa de biomassa. Recomendamos que as estimativas de peso seco de amostras preservadas sejam feitas o mais rápido possível. Por fim, considerando as perdas atribuídas à preservação e às variações intraespecíficas da biomassa dos organismos, recomenda-se a aplicação de fatores de correção uma vez que amostras preservadas são importantes na avaliação de mudanças de longo prazo nas comunidades biológicas.

Abstract: Aim In this study, the effect of preservation time on total body length and dry weight of adult specimens of the neotropical cladoceran Ceriodaphnia silvestrii preserved with 4% formalin solution were examined. Methods The relationship between these variables was examined under increasing gradual time effects (i.e. 7, 30, and 60 days) after preservation using linear models and analysis of variance. Results Total body length did not statistically differ between fresh and preserved cladocerans at any preservation time, whereas dry weight was drastically reduced with increasing preservation time, with 15, 47 and 57% weight losses. Length-weight relationships were significantly and positively related in all treatments, though higher values of slope were found for fresh and 7 days samples. Conclusions We highlight that, for Ceriodaphnia silvestrii, the use of the formalin solution as a preservation fixative is not adequate when the major interest is biomass estimation. Also, we recommend that dry weight estimations from preserved samples should be done as soon as possible. Finally, considering the preservation losses and intra-specific composition of organisms, the application of correction factors is advised since preserved samples are important in the evaluation of long-term changes of biological communities.

Abstract Despite the rising interest in cladoceran biogeography worldwide, many species distributions are still unknown to science, especially in naturally rich freshwater of the Neotropics. Herein we present a checklist of the taxa, giving the distributions of the valid species throughout 13 hydrographic basins within the two freshwater ecoregions of Northeastern Mata Atlântica and São Francisco. Superorder Cladocera comprises 72 known species in Bahia State classified into two orders: the Anomopoda, represented by Chydoridae (36 spp), Daphniidae (7), Macrothricidae (6), Bosminidae (4), Moinidae (3) and Ilyocryptidae (2); and Ctenopoda, represented by Sididae (8 spp). Species from the orders Onychopoda and Haplopoda are still lacking in Neotropical waters. The first compilation of the data on the Cladocera of Bahia, Brazil, is represented by this checklist and contains 38 new records for the state. Critical remarks on species distributions, as well as detailed information on sampling sites and geographic coordinates are also included.