Phylogenetic and morphological analyses of the Manabí oyster, an emerging aquaculture species in Ecuador, reveal its identity as Crassostrea corteziensis (Hertlein, 1951)

The Manabí oyster (Crassostrea sp.) is considered a potential emerging aquaculture species for estuarine environments in the Tropical American Pacific, particularly in equatorial regions. While preliminary studies on its biological feasibility for cultivation are underway and although its mitochondrial genome has been recently described, its taxonomic identity has remained unclear until now. Here we conducted a comparative morphological study of natural and cultured Manabí oysters with Crassostrea corteziensis from Boca de Camichín, Nayarit, Mexico, and performed molecular identification using mitochondrial DNA genes (cytochrome c oxidase subunit I and 16S ribosomal RNA) to construct phylogenetic trees. Although evident morphological differences exist between the Manabí oyster—primarily a protuberance on the right valve of natural Manabí oysters and a blackish color in both natural and cultured Manabí oysters—and the oyster from Boca de Camichín, their phylogenetic analysis provides conclusive evidence that the Manabí oyster from the Chone River in Ecuador is conspecific with Crassostrea corteziensis. This clarification has direct implications for aquaculture planning and policy.