New arcid species belonging to the genera Paranadara gen. nov., Acar and Asperarca (new record) are described for the western Atlantic Ocean based on shell morphology. Paranadara taludae sp. nov., Acar naturezae sp nov., Acar oliveirae sp. nov. and Asperarca tarcylae sp. nov. were collected off north-eastern Brazil between depths of 70 and 690 m, whereas Acar lepidoformis sp. nov. was dredged off the State of Rio Grande do Sul (southern Brazil) at a depth of 141 m. There are no species along the Brazilian coast that are morphologically similar to Paranadara taludae sp. nov. Acar naturezae sp. nov., Acar lepidoformis and Acar Acar oliveirae sp. nov. are similar to this genus due to shape, ligament, presence of concentric lamellae cut by radial threads, a broad dorsal area and a markedly narrowed anterior region in comparison to the posterior region, which is strongly expanded. Asperarca tarcylae sp. nov. is similar to this genus due to the presence of a small edentulous region below the umbo and smooth inner margin.
