Cytochrome C Oxidase Subunit I and II (COI and COII) Sequences Support Recognition of Papilio chikae Igarashi and Papilio hermeli Nuyda as Distinct Species

Abstract

Papilio chikae and P. hermeli are two endemic swallowtail butterflies in the Philippines found primarily in the Cordillera region and Mindoro Island, respectively. Their species status is still subject to debate due to opposing interpretations of their genitalia and morphological traits. This study aims to delineate these taxa through the use of mitochondrial cytochrome C oxidase subunit I(COI) gene marker, with additional information on their cytochrome C oxidase subunit II(COII) gene. The COI nucleotide sequences from our Philippine P. chikae samples were surprisingly identical to P. hermeliEF514465.1 on the GenBank, whereas our P. hermelisamples showed a 100% similarity with P. hermeliEF514464.1.Based on our phylogenetic analysis, P. chikae and P. hermeli exhibit distinct COI barcodes supported by a high bootstrap value (85%). The P. hermeli voucher specimen with GenBank Acc. No. EF514465.1 clustered with our P. chikae samples, separate from the cluster containing our P. hermelispecimens. Nonetheless, the 3.1–3.4% genetic distance observed in the COI region supported by the formation of two separate clusters suggests species status for these taxa. Moreover, species-specific molecular markers obtained from the COII region displayed a 2.4% distance between these two taxa. These molecular markers could therefore be utilized to distinguish P. chikae from P. hermeli. Nevertheless, a thorough examination of their morphology, behavior, and ecology is still imperative to firmly establish their taxonomic status.