Molecular phylogeny of Scutellaria (Lamiaceae; Scutellarioideae) in Iranian highlands inferred from nrITS and trnL-F sequences

Abstract

Scutellaria with about 360 species is one of the largest genera of Lamiaceae. The Iranian highlands accommodate about 40 Scutellaria spp., and is considered as one of the main centers of diversity of the genus. Here, we present a phylogenetic study for 44 species of Scutellaria especially from Iranian highlands, representing major subgeneric taxa, based on nuclear ribosomal ITS and trnL intron and trnL-F intergenic spacer using Maximum Parsimony (MP) and Bayesian Inference (BI) analyses. The monophyly of Scutellaria is confirmed in our study, but Scutellaria subg. Scutellaria is shown to be paraphyletic with S. subg. Apeltanthus embedded within it. Moreover, our results reveal that S. subg. Apeltanthus is paraphyletic including one accession of S. repens of S. subg. Scutellaria nested within. In addition, the two sections of S. subg. Apeltanthus, i.e. sect. Apeltanthus and sect. Lupulinaria, are not supported as monophyletic by our plastid and nuclear topologies. Thus, the subgeneric classification of Scutellaria which is mainly based on morphological characters such as the type of inflorescence, shape of calyces, presence of a scutellum and a bladder-like appendage on the upper calyx lip is not supported by our molecular data. Additionally, our phylogenetic study corroborates Paton’s finding on primitive position of S. sect. Scutellaria, but disagrees with the intermediate position of S. sect. Salviifolia between S. subg. Scutellaria and S. subg. Apeltanthus.