Identity of the enigmatic oyster <i>Saccostrea cuccullata</i> (Bivalvia: Ostreidae)

ABSTRACT Oysters (family Ostreidae) are a key group in shallow water tropical and warm temperate communities throughout the world. Many species are ecosystem engineers of considerable economic and environmental importance. The subfamily Saccostreinae currently contains the single genus Saccostrea. Species taxonomy is poorly understood, with numerous species having been described. As many were thought to be synonyms, Saccostrea cuccullata was generally accepted to be a widespread species in the Indo-West Pacific and South Atlantic Ocean. Recent DNA studies have however demonstrated the “species” is actually a complex of different genetic lineages. We provide the first DNA sequences of S. cuccullata from the type locality of Ascension Island in the central South Atlantic Ocean and demonstrate that it is distinct from all other published lineages. The present paper presents useful data for developing a better understanding of this complex genus.