Small Nuculidae (Bivalvia) with functional primary hinge in the adults

Two paedomorphic species of the family Nuculidae are described from the Western Mediterranean and the Canary Islands respectively. They have an adult size closc to 1 mm and maintain a functional set of 9—12 primary teeth, jointly with a small number of the usual taxodont teeth of the nuculids. The larger species Nucula nucleus and others have lost such teeth at the same size.
The two new species have a smooth ventral margin, a character shared with juveniles of all species with a crenulated margin in adult stage. The value of this character at the generic level is discussed; the new species are found to share more characters with Nucula s. str. than with larger species with a smooth margin in the adult stage currently classified as Ennucula, and thus are provisionally retained in the genus Nucula.