A phylogenetic and morphological study of Polystachya sect. Superpositae (Orchidaceae) with description of a new species from Cameroon

Abstract

Polystachya section Superpositae is a group of montane and submontane African epiphytes with thirteen species (including the newly described in this paper). During a scientific expedition to Bamenda Highland, Cameroon a new species, Polystachya bamendae, was found and it is described here. The new entity was compared with 398 herbarium specimens representing the section, including the type collections. The molecular analyses of the ITS and matK strongly support the results of morphological studies and reveal close relationship between the new species and the species of the section Superpositae. Two hypotheses supporting function of the matK gene in the examined species are presented. The phylogenetic and morphological relation of Polystachya bamendae to P. lindblomii and P. superposita is discussed. The distribution range of the section is analyzed and a discussion about the distribution of the species is presented. A distribution map of the section and dichotomous key to the species of Superpositae are provided. The occurrence of the species of the section in two Biodiversity Hotspots (Guinea Forests of West Africa and Eastern Afromontane) is discussed. © 2013 The Author(s).