The generic position of Stachys tibetica Vatke and amalgamation of the genera Eriophyton and Stachyopsis (Lamiaceae subfam. Lamioideae)

We have investigated the phylogenetic position of Stachys tibetica by use of both plastid (rps16 intron, trnL-F region and matK) and nuclear ribosomal (ITS) DNA sequence data and both parsimony and Bayesian phylogenetic methods. All data corroborate that S. tibetica is extraneous in Stachys (tribe Stachydeae) and suggest a phylogenetic affiliation in a different lamioid tribe, Lamieae. The molecular data suggest that the species is most closely related to the genus Stachyopsis, while most of the morphological data suggest an intermediate position between Stachyopsis and Eriophyton. Due to difficulties in distinguishing Stachyopsis and Eriophyton, and the possible embedding of the former in the latter genus, we prefer to amalgamate the two closely related genera and refer S. tibetica to the expanded Eriophyton. As a consequence, five new combinations are made: Eriophyton lamiflorum (Rupr.) Brauchler, Eriophyton maleolens (Rech.f.) Salmaki, Eriophyton marrubioides (Regel) Ryding, Eriophyton oblongatum (Schrenk) Bendiksby and Eriophyton tibeticum (Vatke) Ryding.