Complete mitochondrial genome of the blind vent crab Gandalfus puia (Crustacea: Bythograeidae) from the Tonga Arc.

The brachyuran crab Gandalfus puia is a species endemic to the hydrothermal vent fields in the Tonga-Kermadec Arc. In order to understand G. puia at the genomic level, we sequenced its mitochondrial genome (mitogenome) and then compared to other bythograeids. The mitogenome is 15,548 bp in length and exhibits brachyuran-typical gene arrangement. Its protein-coding genes were very similar to other bythograeid species with respect to length, AT content and start and stop codons. Additionally, we compared the mitogenomes of Gandalfus and the closely related Austinograea. The inter-specific nucleotide divergence was 13.4% in Gandalfus and 13.7-14.0% in Austinograea. The inter-generic nucleotide divergence between Gandalfus and Austinograea was 16.3-19.7%. Based on the phylogenetic tree constructed with maximum likelihood and Bayesian inference, bythograeid crabs were recognized as the monophyletic taxon with the high supporting values (100% bootstrap proportions and 1.00 posterior probabilities). These results are useful for understanding the phylogenetic relationships and evolution of bythograeid crabs.