Complete mitochondrial genome of freshwater pearl mussel Lamellidens marginalis (Lamarck, 1819) and its phylogenetic relation within unionidae family.

BACKGROUND: Freshwater mussels play a key role in ecology and are often considered as ecological indicators. Conversely, these molluscs are one of the most threatened groups due to several anthropogenic factors. Knowledge of phylogenetic diversity would assist in formulating effective management and conservation measures. Lamellidens marginalis is one of the most widely used freshwater mussel for pearl production in India. The genomic resources for investigating its evolutionary relationship within the Unionidae family are lacking.

METHODS AND RESULTS: In this study, the f-type mitochondrial genome of L. marginalis was sequenced using the Illumina sequencing platform. The length of the mitochondrial genome was 15,732 bp consisting of 23 tRNAs, 2 rRNAs and 13 protein coding genes. The arrangement of genes was UF1 type and gene overlap was observed between trnG and nad1. Comparative analysis with other Unionidae species showed a high divergence rate in nad6 followed by nad2 atp8 and nad5. The phylogenetic tree supported monophyly of the Unioninae subfamily and L. marginalis (Parreysiinae) formed a sister branch to this subfamily. The divergence time of the Parreysiinae from its most recent common ancestor (MRCA) was placed in the Mesozoic era.

CONCLUSION: This information will be useful for the understanding the evolutionary pattern of the species of Parreysiinae subfamily.