Complete Mitochondrial Genomes of Pentapodus caninus and Lethrinus olivaceus (Spariformes: Nemipteridae and Lethrinidae): Genome Characterization and Phylogenetic Analysis

Complete mitochondrial genomes (mitogenomes) are widely utilized molecular resources for phylogenetic studies. Although research on Spariformes mitogenomes has advanced significantly, there is still relatively little information regarding the molecular data and taxonomic placement of the families Nemipteridae and Lethrinidae. We report and annotate the first complete mitogenomes of <i>Pentapodus caninus</i> (16,866 bp; Nemipteridae) and <i>Lethrinus olivaceus</i> (16,792 bp; Lethrinidae), thereby expanding mitogenomic coverage in two families with limited available genomic data. Both assembled mitogenomes display the canonical vertebrate architecture, comprising 37 functional genes (13 protein-coding genes, 22 tRNAs, and 2 rRNAs) and a control region, with conserved synteny and strand asymmetry (only <i>ND6</i> and eight tRNAs are light-strand encoded). While ATG serves as the primary initiation codon for most PCGs, <i>COX1</i> employs an alternative GTG start codon. Structural analysis of tRNAs revealed that most sequences adopt the standard cloverleaf conformation, with the exception of <i>tRNA-Ser^AGY</i>, which lacks the dihydrouridine (DHU) arm. A rare tandem duplication of <i>tRNA-Val</i> in <i>Lethrinus</i> species highlights the structural variability of spariform mitochondrial genomes. Furthermore, phylogenomic reconstruction using the concatenated 13 protein-coding gene dataset recovered Nemipteridae and Sparidae as sister taxa. In this topology, Lethrinidae was identified as the earliest diverging lineage, basal to the Nemipteridae-Sparidae grouping. Our results not only advance our understanding of the origin and evolution of Spariformes, but also provide valuable information for the molecular phylogeny and taxonomy of teleostean species.