Phylogeny and biogeography of the lamioid mint genus Phlomis L.

Abstract

Abstract Classification of the lamioid mint genus Phlomis L., which comprises more than 100 species distributed in Asia, southern Europe and northern Africa, has so far been the subject of few, mainly morphological studies. The present research represents the first molecular phylogenetic study of the genus in which taxa representative of the entire genus are included. In contrast to considerable morphological and ecological variation among taxa, sequence variation in the trnL intron and the trnL-trnF intergenic spacer was remarkably low, which when analysed, resulted in sparse phylogenetic resolution, especially among the south-west Asian and the Mediterranean taxa. However, these phylogenetic results were still informative regarding Phlomis classification and biogeography. The results support a split of the genus into two separate groups; the taxonomic ranks of these groups as either genera or sections can be disputed. I choose here to recognise these clades as separate genera in order to decrease the taxonomic complexity of Phlomis. The close relationship between Phlomis and Eremostachys Bunge, pointed out by several authors, is confirmed in this study, and in a noteworthy new finding, the small Asian genus Notochaete Benth. is more closely related to Phlomis than previously assumed. Both Eremostachys and Notochaete are in fact nested within one of the clades of Phlomis s.l., here recognised as the genus Phlomoides Moench. Character optimisation analyses based on geographic distributions of all taxa show that the groups obtained by molecular phylogenetic analysis correlate well with biogeography. The results suggest that Phlomis s.l. has a south-west Asian origin in the area around Western China.