EN
Oysters (Ostreidae) manifest a high degree of phenotypic changes, whereby morphology is of limited value for species identification and taxonomy.In the current study we attempt to identify two oyster species that are culturing in the Northwestern coasts of Sri Lanka.By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Sri Lankan coast, and phylogenetically relate these to other Crassostrea sp from different parts of the world. By sequencing of the partial cytochrome oxidase c subunit I gene (COIregion), revealed species of Crassostrea sp at 2 locations along the Sri Lankan coast. An unidentified Crassostrea sp species was found in Gangewadiya and Kandakuliya, thereby forming amonophyletic group, whereasCrassostreasp. from Kandakuliya, Sri Lanka was shown to be more similar to Indian oysters, and Gangewadiya, Sri Lankaspecies is more similar to Malaysian oysters. According to the morphological identification suggested that oyster specimens belonged to same species and themolecular detection method confirmed the gene pool is differentiate damong the population. Analysis of sequences of the mitochondrial control region from oyster species confirmed that the samples belonged to Crassostrea sp.with the different gene population