Notes on the identity of Cardium costatum Linnaeus, 1758, with the description of Cardium maxicostatum spec. nov. from tropical West Africa (Bivalvia, Cardiidae)

It is shown that what is generally considered a single species, the Great ribbed cockle, Cardium costatum Linnaeus, 1758, consists of two clearly different forms, to be separated at species level. Among the available possible type material of C. costatum, which is in agreement with one of these forms, a lectotype is selected. Because no alternative name is available for the remaining form, a new species is here described as C. maxicostatum spec. nov.