The Complete Mitogenome of Xeruca formosensis (Rathbun, 1921) (Crustacea: Brachyura: Ocypodidae), a Fiddler Crab Endemic to Taiwan, with its Phylogenetic Position in the Family.

Xeruca formosensis is a species and genus of fiddler crab endemic to Taiwan, with limited distribution in western Taiwan and the offshore Penghu Islands. This study reports the complete mitochondrial genome (mitogenome) of this species using next-generation sequencing. The mitogenome contains 15,684 bp, comprising 13 protein-coding genes, 22 tRNAs, 2 ribosomal RNAs and a 750-bp intergenic space (control region). The nucleotide composition is biased toward A+T (69.4%). A phylogenetic analysis based on the concatenated protein-coding genes showed that the genera Xeruca Shih, 2015 and Tubuca Bott, 1973 are sister to each other. In addition, the phylogeny of the 16 available mitogenomes in the family Ocypodidae also supports the current systematics of this family based on one nuclear and two mitochondrial markers. As this species inhabits high intertidal mudflats with high temperature and high salinity, mitogenome analyses may help us understand the mechanisms of adaptation to extreme environments, as well as the connectivity of metapopulations based on mitogenomes from different populations.