Integrating Wing Morphometrics and Mitogenomic Sequences Supports Species-level Distinction between Papilio maraho and Papilio elwesi (Lepidoptera: Papilionidae)

The Taiwan Broad-tailed Swallowtail, Papilio maraho, is an endangered species in Taiwan and has been recognized as sister to continental Papilio elwesi. However, the exact species identification between them has remained contentious because of similar genital morphology and only a few DNA diagnostic sites. Here, we integrate wing morphometrics and next-generation sequencing to reevaluate their identification. Our analyses show that hindwing morphology clearly separates these taxa: Papilio maraho has a broader, shorted hindwing with a much higher proportion of red scaling, whereas Papilio elwesi shows a narrower, elongated hindwing with higher proportion of black scaling. Furthermore, phylogenetic relationships and the haplotype network based on 37 mitochondrial genes separates the two taxa into reciprocally monophyletic clusters, further confirming their genetic distinctiveness. The congruence among morphological and genetic evidences strongly supports that Papilio maraho is an independent lineage. Formal recognition at the species level will facilitate more targeted and effective conservation strategies.