Abstract

Though the family Ceratopogonidae is a species-rich group (6346 extant species in 2025) within the Diptera, the complete mitochondrial genomes (mitogenomes) have been characterized for a small number of species. In this study, we sequenced and characterized the complete mitogenomes of Dasyhelea ludingensis (15,687 bp) and Forcipomyia (Lasiohelea) taiwana (17,315 bp) to explore their genomic structure and phylogenetic relationships. Each mitogenome exhibited the typical insect structure: 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and a control region, maintaining the ancestral insect gene arrangement. All PCGs used typical ATN start codons, except for COX1 in D. ludingensis, which was putatively initiated by the atypical AAC codon. Both mitogenomes exhibited a strong A + T bias, with A + T contents of 78.29% in D. ludingensis and 78.89% in F. taiwana, respectively, which affects codon usage and amino acid (AA) composition. Regarding tRNA secondary structures, trnS1-GCU in F. taiwana lacked the dihydrouridine (DHU) arm and contained an unpaired adenine residue in the anticodon stem. Phylogenetic analyses confirmed the taxonomic status of D. ludingensis and F. taiwana at the molecular level. This study provides essential genomic resources for future studies in systematics, phylogenetics, and population genetics of biting midges.