Phylogeny and Taxonomy of Eurya (Ternstroemiaceae) from Taiwan, as Inferred from ITS Sequence Data

Eurya is the largest genus in the Ternstroemiaceae. The 13 Eurya species in Taiwan constitute an important element in various habitats from low to high elevated forests in the island. In an attempt to understand the interspecies relationships and geographical history of these 13 species, we sequenced 123 samples representing 32 Eurya species from Taiwan, the Ryukyus, continental China, and Southeast Asia at the nuclear ITS region. Sixteen species of five other genera of Ternstroemiaceae were also incorporated. Molecular phylogenetic trees show that the Eurya species studied form a monophyletic group, organized into five clades with geographical correlations. All the 17 Eurya species from Taiwan and the Ryukyus studied, except E. loquaiana, together constitute two coherent, but distantly related clades: one clade stands at a basal and isolated position, with four out of its five species endemic to these two regions; they are probably Tertiary elements of northern China or their direct descendants. The other clade is much more advanced and has strong affinity to the Eurya in southeast China, which suggests that the members were probably originated from the Quaternary flora of southeast China. Ecological partitioning is thought to be the major mechanism for the speciation of four Taiwan-endemic species from E. chinensis.