Abstract
The mountainous duskywing, Erynnis montanus, belongs to a lepidopteran family Hesperiidae. The 15,530-bp long complete mitochondrial genome (mitogenome) of the species has the typical gene content of animals (13 protein-coding genes, two rRNA genes, 22 tRNA genes and one major non-coding A+T-rich region). As typical in lepidopteran mitogenome E. montanus mitogenome also contained a high A/T content in the whole genome (81.7%) and the CGA (arginine) as the start codon for the COI gene. Unlike other lepidopteran species, including two sequenced skippers, the E. montanus mitogenome has a unique arrangement tRNASer–tRNAAsn, instead of the tRNAAsn–tRNASer found unanimously in other lepidopteran species, providing a new gene arrangement in Lepidoptera. Such rearrangement probably was likely caused by duplication of gene block tRNASer–tRNAAsn and subsequent random loss of tRNAAsn in the first copy and tRNASer in the second copy, resulting in the arrangement tRNASer–tRNAAsn.