Oysters, as sessile, filter-feeding bivalves, are prevalent in estuarine and coastal ecosystems around the globe. They are crucial for both fisheries and aquaculture, offering significant ecological benefits. However, their genetic diversity and distribution remain largely unexplored. Variability in shell shape adds complexity to species classification, which is affected by both environmental and genetic influences (Fig. 1). While advances in molecular phylogenetics have improved oyster taxonomy and revealed approximately 100 currently recognized species, many taxonomic ambiguities still exist.
This study focused on documenting the presence of small flat oysters belonging to the genus Ostrea in the Mediterranean coastal regions of Liguria and Sardinia, Italy. To identify Ostrea species, we utilized 16S rRNA sequence data. Our results provide new insights into the O. stentina species complex and identify O. neostentina, a novel species within Mediterranean coastal areas of Italy. The findings enhance our understanding of the diversity, distribution, and evolutionary dynamics of Ostrea species.