A new species of Macrocypraea (Gastropoda, Cypraeidae) from Trindade Island, Brazil, including phenotypic differentiation from remaining congeneric species.

Macrocypraea mammoth is a new species from Trindade, a remote oceanic island located 1160 km off Espírito Santo, Brazil. This isolated species is described in a detailed morphological scenario that includes all Recent congeneric species. The detailed anatomy of two Recent species, M. zebra and M. cervinetta, were described in a previous paper. The remaining one, M. cervus, is included herein. Brief taxonomical comments on all these species is also included. The new species can be distinguished from other Western Atlantic species by its larger size, proportionally heavier and more solid shell, more rounded and wider outline, longer posterior tapered ending and slightly inflated base; anatomically it has some exclusivities, such as the mantle papillae mostly bearing 3-5 distal aligned projections, osphradium with a shorter branch, modifications in some odontophore muscles, penis with a clear glandular region, and a sac-like bursa copulatrix with a long duct. Based on the comparative analysis, the genus Macrocypraea can be defined by the wide distance between the osphradium and gill; a twofold buccal muscle (mc); a radular ventral tensor muscle (pair m11) surrounding radular sac; and a bursa copulatrix located at middle level of the pallial oviduct. Register ZooBank: urn:lsid:zoobank.org:pub:C8E6E515-508F-47DE-9753-4EA619C1DDFD.