Integrating dna sequences with morphological analysis clarifies phylogenetic position of salvia grandifolia (Lamiaceae): An enigmatic species endemic to southwestern china

Premise of research. Salvia grandifolia is a narrowly endemic species known only from the Hengduan Mountains of southwestern China. Previous studies have shown that East Asian Salvia species form a clade, Salvia subg. Glutinaria, and suggested that S. grandifolia, on the basis of geographical distribution, should be included within Glutinaria. Calyx and staminal features, however, indicate that S. grandifolia may be closely related to taxa of subg. Sclarea, subg. Salvia, and the informal subg. “Heterosphace,” which are primarily found in central and southwest Asia, Europe, and the Mediterranean region. Since S. grandifolia is a rare species and has never been included in any molecular phylogenetic studies, the phylogenetic position of this species remains uncertain. Methodology. The phylogenetic position of S. grandifolia was inferred using DNA sequences as well as morphological and cytological evidence. We used two nuclear ribosomal DNA regions (internal transcribed spacers and external transcribed spacers) and one chloroplast marker (rpl32-trnL) in concert with maximum likelihood and Bayesian inference approaches to examine phylogenetic relationships. Pivotal results. The chromosome number of somatic cells within S. grandifolia was 2n=4x=40. Rather than being grouped with taxa of the East Asian subg. Glutinaria as expected, S. grandifolia was embedded within subg. Sclarea in both nrDNA and cpDNA phylogenetic analyses. Conclusions. Phylogenetic and morphological evidence indicates that S. grandifolia is a member of subg. Sclarea, and thus East Asian Salvia is nonmonophyletic in a geographic sense. Dispersal of Salvia from southwest Asia to East Asia has ostensibly occurred at least twice.