Decoding the complete mitochondrial genome of Hyalomma lusitanicum (Parasitiformes: Ixodidae)

The complete mitochondrial genome of Hyalomma lusitanicum Koch was assembled, annotated, and comprehensively characterized to investigate its genomic organization and evolutionary features. SRA reads of Hy. lusitanicum were retrieved from the NCBI database and assembled using the “map to reference” approach with the Hy. rufipes mitochondrial genome. Genome completeness was confirmed through comparative BLAST analyses with available Acari mitochondrial genomes. The circular mitochondrial genome of Hy. lusitanicum is 14.742 bp in length and comprises 13 protein-coding genes (PCGs), 22 transfer RNA (tRNAs), two ribosomal RNA genes (rRNAs), and two non-coding control regions. The mitogenome exhibits a pronounced AT bias and negative AT and GC skewness values. Two distinct control regions were identified. Mitogenome organization of Hy. lusitanicum was identical to Hyalomma mitotype M55. Protein-coding genes displayed strong nucleotide compositional biases, variation in start and stop codon usage, and a predominance of hydrophobic amino acids. The lengths and nucleotide compositions of tRNA genes were variable, and secondary structure predictions identified several truncated tRNAs lacking D- and/or T-arms. The presence of truncated mitochondrial tRNAs presence in Hy. lusitanicum represents an unexpected structural feature within Parasitiformes. The rRNA genes showed nucleotide compositions consistent with overall mitogenomic bias. Additionally, conserved and lineage-specific intergenic spacers, gene overlaps, transcriptional motifs, and tandem repeat sequences were detected throughout the mitogenome. Collectively, this study specifies a mitochondrial genome resource for Hy. lusitanicum and offers new insights into mitochondrial genome evolution and tRNA structural diversity in ticks.