Morphological and molecular identification of pearl oysters along the Saudi coast of the Red Sea

This study aimed to identify and differentiate the pearl oyster species along the Saudi coast of the Red Sea using morphology and molecular phylogeny. Pearl oysters were collected from six stations, covering different habitats along the Saudi Arabian coast on the Red Sea. Morphological examination included external and internal shell characteristics such as shape, color, and size. Molecular phylogenetic analysis was based on the mitochondrial cytochrome oxidase subunit I (COI) gene. The analysis of the morphological features revealed the presence of two distinct species in the family Pteriidae, Pinctada radiata and Pinctada margaritifera. P. radiata is a small-sized species with significant morphological variability, particularly among spat and juvenile stages. In contrast, P. margaritifera , a large-sized species, exhibited relatively uniform shell morphology with minor differences in structure, color, and size. Nevertheless, the findings of the phylogenetic analysis imply that samples identified morphologically as P. margaritifera may include at least two genetically distinct lineages. Hence, it is crucial to intensify efforts for further comprehensive studies using multiple genetic markers and corroborating nuclear data to understand the taxonomic diversity, evolutionary relationships, and biogeographic patterns of pearl oysters in the Red Sea and surrounding areas.