DNA Barcoding of the Palaearctic Elfin Butterflies (Lepidoptera, Lycaenidae) with a Description of Four New Species from Vietnam †

SIMPLE SUMMARY: We studied the Palaearctic elfin butterflies, a group of hairstreaks (family Lycaenidae, subfamily Theclinae, tribe Eumaeini) comprising about 50 species belonging to three genera, Ahlbergia Bryk, 1947, Cissatsuma Johnson, 1992, and Novosatsuma Johnson, 1992, known mostly from China. Members of this group are still underexplored, and the taxonomy of the Palaearctic elfin butterflies is complicated both at the species and the generic level. We performed an analysis based on a 658 bp region of the COI mitochondrial gene, covering the previously considered genera Ahlbergia, Cissatsuma, Novosatsuma and Callophrys Billberg, 1820, in order to properly discriminate the Palaearctic elfin butterfly species and reveal their phylogenetic positions. The phylogenetic analysis revealed Holarctic Callophrys sensu lato as a strongly supported monophyletic group, but none of the usually treated Palaearctic elfin butterfly genera was recovered as a monophyletic unit. Additionally, we revealed and described four new species of Palaearctic elfin butterflies from Northeast Vietnam. ABSTRACT: Phylogenetic analysis is provided for the first time for 12 species of Palaearctic elfin butterflies, members of the previously recognized genera Ahlbergia Bryk, 1947, Cissatsuma Johnson, 1992, and Novosatsuma Johnson, 1992, based on the barcoding region of the mitochondrial cytochrome C oxidase subunit I gene (COI). Comparison of the COI barcodes revealed very low levels of genetic divergence between the species of the Palaearctic elfin butterflies and Callophrys Billberg, 1820 sensu stricto. COI-based phylogeny revealed that Palaearctic Callophrys and the Palaearctic elfin butterflies, except Cissatsuma, are polyphyletic. Four new sympatric species, namely, Callophrys (Ahlbergia) hmong sp. n., C. (A.) tay sp. n., Callophrys (Cissatsuma) devyatkini sp. n. and C. (A.) dao sp. n. are described from Ha Giang Province, North Vietnam, based on wing colouration, the morphologies of the male and female genitalia, and differences in COI sequences. Discovery of the new species expands the distribution range of the group towards the southeast, beyond the Palaearctic region.