The complete mitochondrial genome of Huananpotamon lichuanense (Decapoda: Brachyura) with phylogenetic implications for freshwater crabs

In the present study, we determined the complete mitochondrial genome of Huananpotamon lichuanense (Decapoda: Brachyura) for the first time. The genome is 15,380bp in length and typically consists of 37 genes. When the gene order was compared to the ancestral crustacean type, two tRNA genes (tRNAHis and tRNAGln) were rearranged in H. lichuanense, and the translocation of tRNAGln appeared only in Potamoidea crabs, such as Geothelphusa dehaani and Sinopotamon xiushuiense, supporting the monophyly of the Potamoidea superfamily. Thirteen protein-coding genes and 2 rRNA genes were divided into five complexes to perform the phylogenetic analysis, and the results showed that the trees constructed by complex I (ND1–ND6 and ND4L), complex IV (COX1–COX3) and rRNA genes better accord with the morphological classification system, suggesting that molecular markers of higher-level phylogeny can be developed in these three complexes in the future. The estimated divergence time for freshwater crabs is approximately 133.58Ma, and G. dehaani from Japan diverged from the freshwater crabs of mainland China approximately 60.66Ma. A selective pressure analysis based on current data revealed obviously increasing dN/dS ratios (except for ATP6 and ND4L) of freshwater crabs, and the accumulation of nonsynonymous mutations suggests that terrestrial habitats provide a relatively relaxed selective pressure environment for this group. •The mitochondrial genome of Huananpotamon lichuanense was determined and the characteristics were described and analyzed.•The three Potamoidea crabs share a peculiar translocation of tRNAGln and this rearrangement supports the monophyly of the Potamoidea superfamily.•The phylogenetic trees constructed by complex I (ND1–ND6, ND4L), complex IV (COX1–COX3) and rRNA genes better accord the morphological classification system.•The divergence time estimation implies that the Brachyura crabs diverged in the early Triassic; the freshwater crabs diverged approximately 133.58Ma.•The selective pressure analysis revealed obvious increasing dN/dS ratios of PCGs (except for ATP6 and ND4L) of freshwater crabs.