Abstract The ostracod genus Bradleya Hornibrook is an important taxon of Cenozoic assemblages, occurring practically in all oceanic regions. The wide distribution both in shallow and deep waters turns Bradleya interesting for studies involving phylogeny and paleoceanography. The present work aims at the study of fossil and recent species in South America and adjacent regions, based on bibliographic review and the restudy of samples from the Brazilian continental margin, the Navidad Formation (lower Miocene) and El Peral Beds (meso-upper Miocene), both cropping out in the Central Chile. The chronostratigraphic, (paleo)bathymetric and (paleo)zoogeographic distribution of the species is reviewed and updated. The bridge composition was studied in all species recorded and revealed to be important taxonomic character. The taxa identified were gathered into three morphological groups: two proposed previously (i.e., the dictyon-group and the arata-group) and a new one in the present work (i.e., the normani-group). The dictyon-group and the arata-group gather deep-sea species, while the normani-group is predominantly neritic, including most of the species of Brazilian margin. Bradleya victorjarai sp. nov. is proposed for the Miocene of Chile, and Bradleya ybate (Bergue et al.) is reassigned to Rigracythere gen. nov. Questionable or misidentified species ascribed to Bradleya are briefly discussed.

Abstract Bathybic ostracods (i.e., bathyal and abyssal assemblages) are important indicators of temperature and productivity changes of Cenozoic marine ecosystems. The present work presents the first study on Quaternary ostracods of the Camamu Basin, off the state of Bahia, northeastern Brazilian continental margin. The analysis of 59 samples from the piston-core CMU 14 (14°24’S, 38°49’W; 965 m water depth), revealed rich and abundant assemblages. The 14C accelerator mass spectrometry (AMS) dating indicates that the studied interval covers the last 108 kyr, corresponding to the oxygen stable isotope stages (MIS) 5 to 1. Comparison with data from previous publications allowed discernment of three groups of ostracod species in CMU 14: Pandemic Group of species registered in more than one oceanic basin; Atlantic/Mediterranean Group of species restricted to the Atlantic Ocean and Mediterranean; and Brazilian Group of species restricted to the Brazilian continental margin). Four new species are herein proposed: Cytherella pindoramensis sp. nov., Ambocythere amadoi sp. nov., Pseudobosquetina pucketti sp. nov., and Bythoceratina bonaterrae sp. nov. Ostracod occurrences reveal the influence of glacial/interglacial cycles on assemblages composition. Interglacial stages 5 and 1 in the Camamu Basin are characterized by the association Bythocypris affinis–Cytherella pindoramensis sp. nov.–Cytheropteron perlaria–Bradleya dictyon; glacial stages (i.e., 2 to 4) register decreased diversity, possibly due to lower oceanic productivity.

Of a total fauna of 95 species of benthic Ostracoda recovered from dry sediments from the southern Brazilian continental shelf, 8% belong to the Family Thaerocytheridae. Six species assigned to this family are discussed and figured in this paper; four of these, Bradleya pseudonormani, B. kaesleri, Muellerina cribrosa and Quadracythere nealei are described as new, while Brasilicythere reticulispinosa and Quadracythere eichlerae were described for the first time from the Quaternary of Pelotas Basin, in southern Brazil. Most of these species are restricted to the southern part of the Southwest Atlantic Ocean, and their geographical distribution ranges from the southern Brazilian continental shelf, in Rio de Janeiro State (21ºS), to the Argentinian continental shelf (52ºS). Three species are restricted to the southern Brazilian continental shelf: B. kaesleri, M. cribrosa. and Q. nealei, while three other species have fossil records: B. reticulispinosa (Oligocene to Recent), Q. eichlerae and B. kaesleri (both Holocene to Recent).

De las 95 especies de ostrácodos bentónicos recuperadas en muestras secas de sedimentos provenientes de la parte sur de la plataforma continental brasileña, 8% pertenecen a la Familia Thaerocytheridae. De éstas Bradleya pseudonormani, B. kaesleri, Muellerina cribrosa y Quadracythere nealei se describen e ilustran por primera vez. Brasilicythere reticulispinosa y Quadracythere eichlerae fueron descriptas para el Cuaternario de la Cuenca de Pelotas, en el sur de Brasil. La distribución geográfica de la mayoría de las especies comprende desde la Plataforma Sur Brasileña, en el Estado de Río de Janeiro (21ºS) hasta la Plataforma Continental Argentina (52ºS). Bradleya kaesleri, M. cribrosa y Q. nealei están restringidas a la parte sur de la Plataforma Continental Brasileña. Tres especies tienen registro fósil: B. reticulispinosa (Oligoceno a Reciente), Q. eichlerae y B. kaesleri (ambas, Holoceno a Reciente).

Ostracods were collected on Sargassum sp. from the littoral of São Sebastião, São Paulo State, southeastern Brazil. A new species, Aurila ornellasae, is illustrated and described based on a population with various instars and adult specimens. This is the first living species of this genus described from Brazil. A brief discussion on the systematics of the genus Aurila Pokorný, 1955 and its allied genera is presented.