De Novo Assembly and Comparative Mitochondrial Genome Analysis of Three Salt Marsh Specialist Ground Beetle Species (Coleoptera: Carabidae)

ABSTRACT

Ground beetles ( Carabidae ) are traditionally used as bioindicators in ecological and evolutionary studies. However, few complete mitochondrial genomes are currently available for this group. In this study, 10 individuals of the salt marsh‐specialist species Bembidion minimum , Dicheirotrichus gustavii , and Pogonus chalceus were sequenced, resulting in nine successfully de novo assembled mitochondrial genomes. The specimens were collected from coastal salt marsh habitats in northern Germany, where they occur in similar coastal environments and represent sympatric salt marsh‐associated Carabidae. Multiple individuals per species were included to ensure assembly consistency and improve robustness of the de novo mitochondrial genome reconstruction. All nine successfully assembled mitochondrial genomes ranged from 16,204 to 17,398 bp in length and contained the typical and identical set of 13 protein‐coding genes, 22 tRNA genes, and 2 rRNA genes, all arranged in the conserved insect gene order. All assembled genomes showed a strong AT‐bias with GC contents of approximately 20%, which was also reflected in the relative synonymous codon usage (RSCU), as preferred codons frequently ended with adenine. Phylogenetic analyses consistently recovered strongly supported monophyletic clades for all three species (BS = 100), while interspecific relationships within Carabidae were weakly to moderately supported, with bootstrap values ranging from approximately 27 to 66. These results indicate that these carabid mitochondrial genomes follow the general structural and compositional patterns known from other Coleoptera. These assemblies add to the limited mitochondrial reference data currently available for Carabidae and may support future comparative, population genetic, and evolutionary analyses.