Research paperThe complete mitochondrial genome of the golden mussel Limnoperna fortunei and comparative mitogenomics of Mytilidae

- L. fortunei mitogenome presents one extra copy of tRNALys not yet described for any other Mytilidae sequenced up to date.
- L. fortunei mitogenome seems to code a pseudo atp8 gene.
- Perna perna and Perna viridis don't seem to be a sister group in a mitogenome phylogenetic perspective.
- Mytilidae phylogenetics seems challenging as the mitogenomes are not very conserved.

Here we describe the mitochondrial genome of the golden mussel Limnoperna fortunei, an Asian bivalve which has become one of the most aggressive invasive species in Japan and South America. The mitochondrial genome of L. fortunei does not present conserved gene arrangement when compared to the other Mytilidae species suggesting a high degree of gene recombination in the mitochondria of this clade. In addition, the golden mussel mitogenome encodes two copies of tRNALys and presents a putative pseudogene for the atp8 gene sequence that encodes a 27 amino acid peptide containing an in-frame stop codon. The presence of this pseudogene raises the question as to whether atp8 is encoded in some bivalve mitochondrial genomes or not. The phylogenetic analysis of all complete mitochondrial genomes available from Mytilidae mussels confirmed the close evolutionary relationships among bivalves from the genus Mytilys and placed L. fortunei coming from a more ancestral branch on the family. The supermatrix phylogeny described used the concatenation of all 12 genes from the mitochondria and disputed the monophyly of the genus Perna, as Perna perna was shown to be more closely related to Brachidontes exustus than to Perna viridis. The comparative analysis of mitogenome synteny also confirmed the polyphyly of the genus Perna. The complete and annotated mitogenome has been published in GenBank under the accession number KP756905.