The genus Haplocytheridea has a wide stratigraphical distribution, occurring from the Cretaceous to Recent. Although the genus has a wide paleobiogeographical distribution it is restricted to the circumtropical regions occuring, mainly, in the North and Central America. This is the first record of this genus in Brazil occurring in the carbonate rocks from Pirabas Formation (Early Miocene) Pará state, northern part of the Brazilian coast. Ten species were identified: five are very similar to the species described to others localities from Europe, North, Central and South America: Haplocytheridea cf. H. larosaensis; H. aff. C. multipunctata; H. cf. dacica elegantior, H. cf. H. placentiaensis and H.? cf. C. (Leptocytheridea) hopikinsi; three are described as new species: H. sandbergi n. sp., H. pirabensis n. sp. and H. sinuosa n. sp.; and others two species were left in open nomenclature H. sp.1 and H. sp.2. The distribution of the genus Haplocytheridea in the studied area showed a cyclical depositional sequence of transitional/coastal to marine neritic paleoenvironments. Haplocytheridea is normally associated to nearshore deposits in tropical, carbonate shallow marine waters and sometimes is associated with coral reefs. Its descontinuous distribution in the studied sequence attests to T-R cycles conditions in the Quarry B-17 sequence.
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