MOLECULAR IDENTIFICATION OF CRYPTIC SPECIES OF OYSTERS (GENUS Crassostrea SACCO, 1897) IN THE NORTHEAST ATLANTIC COAST OF BRAZIL

Oysters of the genus Crassostrea Sacco, 1897 are widely distributed worldwide, being important extractive and cultivation resources in Brazil. Because they have high phenotypical plasticity and congeneric similarity, identifications based on shell morphology are not always safe. The goal of this study was to identify the oysters of the Bahia State, northeast Brazil, using the molecular tools Polymerase Chain Reaction, Restriction Fragment Length Polymorphism, DNA sequencing and phylogenetic analysis. Oysters were collected at 12 sampling stations, from October 2014 to March 2015 and included samples of rhizomes (aerial roots)/stems of the red mangrove Rhizophorae mangle L. and in the sediment near to the underground roots of this one, on berths, natural rock outcrops near the mangrove swamp and in three oyster crops. It was confirmed the presence of two species of oysters: Crassostrea rhizophorae (Guilding, 1828) and C. gasar (Deshayes, 1830) and that the latter was genetically identical to C. brasiliana reported in previous studies on the Brazilian coast. There was no co-occurrence of the two species on the same substrate, but these were found in nearby environments at two sampling points. Crassostrea rhizophorae was observed on the rhizomes/stems of R. mangle, as well as on artificial concrete walls (berths). The semi-buried oysters near R. mangle's subterranean roots and adhered to small rocks of a rocky outcrop were C. gasar, which was also the exclusive oyster of the crops.