Structural Features and Mitogenome-Based Evolutionary Insights into Acanthopleura loochooana (Polyplacophora: Chitonidae)

Acanthopleura loochooana is a widely distributed intertidal chiton in the northwestern Pacific, yet its mitochondrial genomic architecture and evolutionary position within Chitonidae have not been comprehensively evaluated. In this study, we sequenced and analyzed the complete mitochondrial genome of A. loochooana using next-generation sequencing. The mitogenome is a circular double-stranded DNA molecule of 15,295 bp that contains the typical 37 mitochondrial genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes, and 2 ribosomal RNA genes. Codon usage patterns show a clear preference for A- or U-ending codons, consistent with trends observed in other polyplacophoran mitogenomes. Phylogenetic analyses based on concatenated sequences of the 13 mitochondrial PCGs under Bayesian frameworks recovered congruent topologies with strong nodal support. A. loochooana was placed in a well-supported clade with Liolophura japonica and A. vaillantii, providing a reference within Acanthopleurinae. These results provide the complete mitochondrial genome of A. loochooana and contribute new mitogenomic data to the currently limited dataset of Polyplacophora, offering additional insights into mitochondrial genome organization and phylogenetic relationships within Acanthopleurinae.