Characterization of the Complete Chloroplast Genomes of Buddleja colvilei and B. sessilifolia : Implications for the Taxonomy of Buddleja L

Hook.f. & Thomson (Scrophulariaceae) is a threatened alpine plant with a distribution throughout the Himalayas, also used as an ornamental plant. The name B.S. Sun ex S.Y. Pao was assigned in 1983 to a plant distributed throughout the Gaoligong Mountains, but the name was later placed in synonymy with in the . In this study we sequenced the complete chloroplast (cp) genomes of two individuals of and three individuals of from across the range. Both molecular and morphological analysis support the revision of . The phylogenetic analysis constructed with the whole cp genomes, the large single-copy regions (LSC), small single-copy regions (SSC), inverted repeat (IR) and the nuclear genes 18S/ITS1/5.8S/ITS2/28S all supported as a distinct species. Additionally, coalescence-based species delimitation methods (bGMYC, bPTP) using the whole chloroplast datasets also supported as a distinct species. The results suggest that the lineage was early diverging among the Asian species. Overall gene contents were similar and gene arrangements were found to be highly conserved in the two species, however, fixed differences were found between the two species. A total of 474 single nucleotide polymorphisms (SNPs) were identified between the two species. The Principal Coordinate Analysis of the morphological characters resolved two groups and supported as a distinct species. Discrimination of and using morphological characters and the redescription of are detailed here.