The mitochondrial genome sequence of a deep-sea, hydrothermal vent limpet, Lepetodrilus nux, presents a novel vetigastropod gene arrangement

While mitochondrial (mt) genomes are used extensively for comparative and evolutionary genomics, few mt genomes of deep-sea species, including hydrothermal vent species, have been determined. The Genus Lepetodrilus is a major deep-sea gastropod taxon that occurs in various deep-sea ecosystems. Using next-generation sequencing, we determined nearly the complete mitochondrial genome sequence of Lepetodrilus nux, which inhabits hydrothermal vents in the Okinawa Trough. The total length of the mitochondrial genome is 16,353 bp, excluding the repeat region. It contains 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a control region, typical of most metazoan genomes. Compared with other vetigastropod mt genome sequences, L. nux employs a novel mt gene arrangement. Other novel arrangements have been identified in the vetigastropod, Fissurella volcano, and in Chrysomallon squamiferum, a neomphaline gastropod; however, all three gene arrangements are different, and Bayesian inference suggests that each lineage diverged independently. Our findings suggest that vetigastropod mt gene arrangements are more diverse than previously realized.