The First Complete Mitogenome Characterization and Phylogenetic Implications of Elops machnata (Teleostei: Elopiformes: Elopidae)

This study presents the first complete mitochondrial genome characterization of <i>Elops machnata</i> (Teleostei: Elopiformes: Elopidae), a basal teleost lineage critical for understanding early actinopterygian evolution. The assembled mitogenome, deposited under GenBank accession number PV294982, spans 16,712 bp and exhibits the canonical vertebrate mitochondrial gene organization, comprising 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. Base composition analysis revealed 22.71% A, 17.36% C, 29.82% T, and 30.11% G, with a slight AT bias (A + T = 52.53%). Codon usage analysis of the 13 protein-coding genes identified CUA (L), CGA (R), GCC (A), and GGA (G) as the most frequent codons, with a pronounced preference for adenine at the third codon position. Amino acid composition analysis across 23 Elopomorpha species revealed consistently high leucine contents, and tRNA secondary structure prediction showed 21 tRNAs forming typical cloverleaf structures, except for <i>trnS1</i>(gct), which lacks the dihydrouridine (DHU) arm. Phylogenetic reconstruction using maximum likelihood and Bayesian inference methods, based on concatenated mitochondrial protein-coding genes from 23 Elopomorpha species, placed <i>E. machnata</i> in a well-supported clade with <i>Elops hawaiensis</i>, confirming their close evolutionary relationship. This study not only provides essential genomic resources for <i>E. machnata</i> but also resolves key gaps in the mitochondrial genome and improves phylogenetic understanding of Elopomorpha.