The work intends to contribute to the taxonomic studies of the genus Cytheridella and the increase in the record of associated genera of fossiliferous localities in deposits of the Solimões Formation, municipality of Tabatinga, Amazonas, Brazil, CI assisting in paleoenvironmental refinement and its previous one with outcrops of adjacent areas in the Brazil, Peru and Colombia. The were prepared and analyzed using conventional techniques for studies of calcareous microfossils. The material under study comprises 11
those from collections carried out in 2011, within the project "Survey of fossiliferous localities in the Neogene of the Western Amazon, municipality of São Paulo Olivença, in the state of Amazonas, Brazil". The study verifies to verify an abundant ostracofauna, accounting for about 9,411 specimens, however, little diverse, represented by the genera Cytheridella, Penthesilenula and Cyprideis characteristic of myxoaline and fluviolacustrian environments. From the quantitative analysis it was possible to observe the predominance of the genus Penthesilenula (48.67%), followed by Cyprideis (40.8%) and Cytheridella (10.53%). The genus Cytheridella, focus of this study, is represented by the species Cytheridella danielopoli, with variation in carapace ornamentation (lisae ornamentada) and good preservation status, which probably assumes that they were subjected to a low energy environment, without signs of marked transport. This species was also found in other outcrops of the Solimões Formation, in the municipality of Eirunepé, Amazonas, Brazil, whose paleoenvironmental reconstruction infers lacustrine environments of floodplains and/or abandoned canal, inferring that a study area represents a final deposition phase of the Formation. Solimões, whose age would be from Superior Miocene to Pliocene, matching the previous works. Thus, from this preliminary survey, the need to integrate new discoveries in adjacent areas is pointed out, in order to refine their geological / micropaleontological interpretations.
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