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Sixty-five ostracode species belonging to 41 genera and 17 families were recorded in the outer shelf and upper slope off Rio Grande do Sul and Santa Catarina states, southernmost Brazil, between 100 and 586 m water depth interval. The ostracode occurrences are hypothesized to be influenced by both, the coastal waters and the Antarctic Intermediate Water (AAIW). The taxonomy of some species of Bradleya Hornibrook, 1952, Legitimocythere Coles & Whatley, 1989 and Henryhowella Puri, 1957 previously described in the same study area is revised. Bradleya gaucha sp. nov., Legitimocythere megapotamica sp. nov., Apatihowella acelos sp. nov., Apatihowella capitulum sp. nov., Apatihowella besnardi sp. nov., Apatihowella convexa sp. nov., and Aversovalva tomcronini sp. nov. are herein proposed. Trachyleberis aorata Bergue & Coimbra, 2008 is reassigned to the genus Legitimocythere and Bradleya pseudonormani Ramos et al., 2009 has its diagnosis emended. Bythocypris praerenis Brandao, 2008 is considered a junior synonym of Bythocypris kyamos Whatley et al., 1998a. Apatihowella Jellinek & Swanson, 2003 and Legitimocythere species have well-defined bathymetric distributions and are potential paleoceanographic markers for the Quaternary in the Southern Brazilian Margin.

The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic ostracod fauna. Among them, especially the genus Cyprideis experienced a remarkable radiation. Micropalaeontologic investigations of a 400 m long sediment core (~62 km SW Benjamin Constant, Amazonia, Brazil) permitted a taxonomic revision of about two-thirds of hitherto described Cyprideis species. We evaluate the diagnostic value of shell characters and provide an extensive illustration of the intraspecific variability of species. Based on comparative morphology, the 20 recorded Cyprideis species are arranged in groups and subgroups. The “smooth” group comprises C . amazonica , C . kotzianae , C . kroemmelbeini , C . machadoi , C . multiradiata , C . olivencai , C . paralela and C . simplex ; the “ornate” group C . curucae nom. nov., C . cyrtoma , C . aff. graciosa , C . inversa , C . ituiae n. sp., C . matorae n. sp., C . minipunctata , C . munoztorresi nom. nov., C . pebasae , C . reticulopunctata , C . schedogymnos and C . sulcosigmoidalis . Five species have been revalidated, two renamed, two synonymised and two are new descriptions. Along with 10 further formally established species, for which a review is pending, Cyprideis keeps at least 30 endemic species in that region during Miocene times. Up to 12 Cyprideis species have been found to occur sympatrically, representing >90 % of the entire ostracod fauna. Ostracod index species enable a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to Cyprideis cyrtoma biozones, corresponding to a late Middle to early Late Miocene age (late Serravallian–early Tortonian).