The largest unassigned regions of the male- and female-transmitted mitochondrial DNAs in Musculista senhousia (Bivalvia Mytilidae)

- Conserved features were found among diverse Mytilidae species mitochondrial CRs.
- Duplicated control regions evolve in concert in the F mtDNA of M. senhousia.
- Number of control regions in a mtDNA might influence its sequence evolution.
- Duplication of the F mitochondrial CR did not affect DUI in M. senhousia.

Musculista senhousia is a marine mussel with doubly uniparental inheritance (DUI) of mitochondria. In this study we analyzed the largest unassigned region (LUR) of its female- and male-transmitted mitochondrial genomes, described their fine characteristics and searched for shared features. Our results suggest that both LURs contain the control region of their respective mitochondrial genomes. The female-transmitted control region is duplicated in tandem, with the two copies evolving in concert. This makes the F-mtDNA of M. senhousia the first Bivalve mitochondrial genome with this feature. We also compared M. senhousia control regions to that of other Mytilidae, and demonstrated that signals for basic mtDNA functions are retained over evolutionary times even among the fast-evolving mitochondrial genomes of DUI species. Finally, we discussed how similarities between female and male LURs may be explained in the context of DUI evolution and if the duplicated female control region might have influenced the DUI system in this species.