The mitochondrial genomes of Pecten albicans and Pecten maximus (Bivalvia: Pectinidae) reveal a novel gene arrangement with low genetic differentiation

• We determined the mitochondrial genomes of two Pecten species.
• A novel gene order rearrangement was revealed.
• Both Pecten mitogenomes showed high similarity, suggesting a recent divergence event.
• Phylogenetic analyses confirmed the sister relationship between genera Pecten and Argopecten.

Scallops (Bivalvia: Pectinidae) comprise more than 350 extant taxa including species of high economic importance. However, its phylogenetic classification remains unclear and so far only 7 scallop mitogenomes have been determined. In this study, the mitochondrial genomes of two congeneric scallop species Pecten albicans and Pecten maximus were determined. Both mitogenomes contain 12 protein-coding genes (atp8 is missing), two ribosomal genes, 20–22 transfer RNA genes, all encoded in the same strand. Overall, both Pecten mitogenomes are highly similar with high nucleotide (93%) and amino acid (98.7%) sequence identity. Both mitogenomes also contain the same gene order arrangement, which is a novel contribution within Pectinidae. The highly similar mitochondrial organization between both Pecten species suggested a recent speciation event. Phylogenetic analysis based on complete protein-coding gene information as well as large synteny gene blocks confirmed the sister group relationship between the genera Pecten (subfamily Pectininae) and Argopecten (tribe Aequipectini).