Phylogenetic position of Wenchengia (Lamiaceae): A taxonomically enigmatic and critically endangered genus

The phylogenetic position of the monotypic genus Wenchengia has long been controversial. It variously has been assigned to a monotypic subfamily Wenchengioideae, treated as a member of subfamily Scutellarioideae, or suggested to be related to Lamioideae or Ajugoideae. The recent rediscovery of Wenchengia alternifolia from its type locality provided an opportunity to infer its phylogenetic position using evidence from two plastid DNA regions (rbcL, ndhF), morphological data, and anatomical and cytological characters. Both the molecular data and a combination of the molecular and the morphological data suggested a close relationship of the genus to a clade consisting of Holmskioldia, Tinnea, and Scutellaria representing Scutellarioideae. This relationship is also supported by a striking similarity in gross morphological, anatomical, and cytological characters between Wenchengia and other genera of Scutellarioideae, suggesting that it should be more appropriate to treat the genus as a member of Scutellarioideae, rather than assigning it to a monotypic subfamily.