Discovery of a peculiar insular race of (Nire, 1920) (Lepidoptera: Lycaenidae) endemic to Yinggeling Mountain of Hainan, suggesting heterogeneous geological history of mountain formation of the island.

A peculiar population of (Nire, 1920) was discovered from the Yinggeling Mountain Mass of central Hainan. Its wing pattern and COI barcode data show considerable distinction from other geographic populations of , including that of Bawangling, approximately only 40 km away and also located in Hainan. The p-distance value of the COI barcode between the Yinggeling and Bawangling populations was 1.1%, considerably higher than the value (0.6%) between Bawangling population and populations in eastern China, where the subspecific name Saigusa, 1993 applies. The population is regarded as a distinct subspecies Lo & Hsu, subsp. nov. The distinctness and high degree of COI haplotype diversity of found in Hainan and Taiwan suggest continental islands may serve as glacial refugees for the butterfly and other organisms during previous glaciations, and the presence of the relict populations of montane butterflies like may provide useful clues towards a better understanding of the geological history of mountain formation within islands.