Molecular phylogeny and historical biogeography of the genus Platycerus (Coleoptera,Lucanidae) in East Asia

The genus Platycerus is a cool temperature zone taxon widely distributed in the Northern Hemisphere. In East Asia, 10, one and 28 species are known in Japan, Korea and China, respectively. Recent studies of Platycerus have revealed the divergence pattern in Japan and South Korea, but that of Chinese Platycerus is unknown. We conducted a phylogenetic and biogeographical study of Platycerus in East Asia, including China, using 68, 87 and 296 sequence data of the nuclear wingless gene, internal transcribed spacer (ITS) region and mitochondrial COI gene, respectively. Although the introgression of mitochondrial genes had been known in Japanese Platycerus, the essential contradiction was not recognized between the phylogenetic trees of nuclear genes and COI in Chinese Platycerus. In the COI tree, the Japanese clade and Asian continental clade diverged around 10.84 million years ago, and four major clades were recognized in the latter. For the shape of the posterolateral corner of the Platycerus pronotum, sharp (S)-type species are distributed in higher latitudinal and lower altitudinal areas than round (R)-type species in the Asian continent. S-type species have evolved from R-type species at least three times in more northerly areas, where the annual amplitude of temperature change is large. The genus Platycerus has been differentiated and speciated by a process unique to South Korea, Japan and China, according to regional topography. Thus, genetic differentiation and speciation in Platycerus are related to latitudinal and altitudinal gradients, as well as the site topographical profile and niche differentiation.