The complete mitochondrial genome of Hyastenus ducator (Majoidea, Epialtidae) and the phylogenetic relationships of Brachyura
The family Epialtidae is the most species-rich lineage within the superfamily Majoidea, but complete mitochondrial genomes (mitogenomes) have been reported for only a few of its members. In this study, we sequenced the complete mitogenome of the decorator crab Hyastens ducator using next-generation high-throughput sequencing, annotated its mitochondrial genes and analysed its genomic organisation. The complete mitogenome of H. ducator is 15 894 bp in length and contains 37 genes, including 13 protein-coding genes (PCGs), two ribosomal RNA genes and 22 transfer RNA genes. The tRNAs range from 52 to 74 bp in length. The nucleotide composition of the complete mitogenome is 34.9% A, 18.2% C, 9.4% G and 37.5% T. A comparison of gene order among species within Majoidea shows that the overall gene order of mitogenomes is largely conserved, but the positions of some short genes and non-coding regions vary to different degrees. Most changes occur in transfer RNA regions and gene orders ranged from highly conserved to extensively rearranged among different lineages. Phylogenetic analyses based on the 13 PCGs robustly placed H. ducator within Epialtidae, clustered it with other epialtid species with strong support and provided new molecular evidence for relationships among families and genera within Majoidea. Overall, this study reports the mitogenome of H. ducator for the first time, clarifies its phylogenetic position, enriches the molecular dataset for the family Epialtidae and provides an important reference for future taxonomic and evolutionary studies of Majoidea.