Mitogenomes of the four holotypes collected 55 years ago.

Giant-Skipper butterflies from the genus (family Hesperiidae) are unusual as their caterpillars feed inside leaves. Relationships among taxa and their names (i.e., if they are species, subspecies, or synonyms) are poorly understood due to phenotypic similarity. DNA sequences are promising to clarify the taxonomic questions, but it is challenging to sequence name-bearing types that are usually old specimens with poorly preserved DNA. Using next generation sequencing, we assembled mitochondrial genomes of four group holotype specimens collected more than 55 years ago and housed pinned and dry in the American Museum of Natural History (New York, NY). We compared the holotype mitogenomes to those we obtained from fresh specimens and the sister species . All but mitogenomes were highly similar to each other (more than 99% identity), suggesting that the four names , , and proposed by H. A. Freeman in 1964 may not refer to species-level taxa. The mitogenomes grouped eastern populations ( and ) together and apart from the western populations (nominal , and ). Mexican A. differs by about 2.5% (about 5% in the COI barcode region) from , and is likely to be a distinct species.