Discovery of the Indo-Pacific oyster Hyotissa hyotis (Linnaeus, 1758) in the Florida Keys (Bivalvia : Gryphaeidae)

Abstract

Recent collections from a shipwreck in ~30 m depth off the Florida Keys recovered an exceptionally large gryphaeid oyster that was identified on morphological grounds as Hyotissa hyotis (Linnaeus, 1758), a common constituent of Indian and Pacific Ocean near-shore faunas. This identification was confirmed by molecular characterisation: the Florida specimen had an almost identical large mitochondrial ribosomal subunit (16S) genotype to that obtained from a western Pacific (Guam) conspecific, differing in only two nucleotide positions that were heteroplasmic in the Guam specimen. Although this species has been variously cited to occur in the western Atlantic, careful examination of these records revealed them to be misidentifications of Hyotissa mcgintyi (Harry, 1985), originally described from south-eastern Florida. Because H. hyotis is much larger than any other regional oyster, it is unlikely to have been overlooked in earlier biotic surveys. It is therefore likely that this specimen, and another recently discovered off West Palm Beach, Florida, stem from a recent undocumented introduction to the western Atlantic.