The nominal species Brachidontes exustus (Linnaeus, 1758) is a cryptic complex. Long polymerase chain reactions and direct sequencing by primer walking was used to determine the complete F type mitochondrial genome of the Gulf of Mexico clade. The genome is 16,600 bp long and contains a single large unassigned presumptive control region, 13 protein-coding genes, 23 tRNA genes, and 2 rRNA genes, all coded for on the heavy chain. As in many other bivalves, there is the addition of tRNA-Met(AUA). The gene order is different from all other mitogenomes known for the family. The B. exustus mitogenome will contribute to a better understanding of the evolutionary history and phylogenetic relationships of the Mytilidae.
Keywords: Bivalvia; marine mussel; mitogenome.