Three new species of Macrocyprina Triebel, 1960 from the Brazilian shallow marine waters are described: M. youngi n. sp., M. rocas n. sp., and M. coimbrai n. sp. These three species differ from all known species of Macrocyprina by the modified male left appendage V, with the conspicuous podomere II not recurved and densely setose. Macrocyprina hawkae Maddocks, 1990 presents a similar modified male left appendage V, but the podomere II is vestigial. Furthermore, Macrocyprina youngi n. sp., reported from Armação de Búzios, Rio de Janeiro, is distinct from the other two new species by the following combined characters: fairly large, elongate carapace; its lateral surface with three or four small subcircular patches and other irregular patches in variable positions; Zenker’s organ with tiny terminal bulb; and hemipenis with subtriangular posterior lamella, with one angle posteroventrally projected. Macrocyprina rocas n. sp., from Rocas Atoll, is characterized by the fairly small, elongate carapace, with the lateral surface bearing one to four central patches; the Zenker’s organ with a small terminal bulb; and the posterior lamella of the hemipenis dorsoventrally elongated. Macrocyprina coimbrai n. sp., recorded from Abrolhos region, Bahia, can be distinguished from the other two new species by its large, elongate-ovate carapace, with the lateral surface presenting three large central patches, and other patches situated in variable positions; the elongated ventrodistal peg of the podomere I of the male left appendage V; the Zenker’s organ with a small terminal bulb; and the hemipenis with a bilobated posterior lamella.
Crustacea, Ostracoda, Macrocyprididae, Macrocyprina, Brazil, shallow waters, marine, new species.