Morphological and molecular data support the separate species status of Syringa fauriei in Korea

Syringa fauriei is an unresolved lilac taxon (Oleaceae) native to specific geographical areas and present in the rivers and valleys of Gangwon province in South Korea. It was first identified on Mt Geumgang by Faurie in 1906 and recognized as an independent species. Nevertheless, S. fauriei has been controversial as a synonymous species for S. reticulata subsp. amurensis without clear evidence. Therefore, we conducted this study on the taxonomic position of S. fauriei by examining the morphological and molecular differences between S. fauriei and its related taxa, the S. reticulata complex. Phylogenetic relationships were also inferred using molecular markers of nuclear ribosomal DNA internal transcribed spacer (ITS1-5.8S-ITS2; ITS) and external transcribed spacer regions. Consequently, S. fauriei and its related taxa were classified into two distinct clades: S. fauriei and the S. reticulata complex. Morphological and molecular data revealed that S. fauriei was endemic to Korea. The species characteristics of S. fauriei were further described for taxonomic re-establishment.