Plagiochila xerophila (Plagiochilaceae, marchantiophyta) – a highly xerophilous new species from the Tibetan Spur (China)

Abstract

Background and aims – The xeric landscapes of the Tibetan floristic province are adverse habitats for leafy liverworts. Here we report on the occurrence of a population of a species of the genus Plagiochila from exposed high-elevation cliffs in the Sichuan Province, China. We assessed its taxonomic distinctiveness and affinities within a morphological and phylogenetic framework. Results and discussion – The population is accommodated in a new species, Plagiochila xerophila Bakalin & Vilnet – probably the most xerophilous taxon within the genus in Asia – and a new section (sect. Xerophilae Bakalin & Vilnet) based on integrative analyses of molecular and morphological traits. The species is characterized by a greenish colour, unexpected given the highly exposed habitat, rigid texture and stem paraphyllia. The closest morphological relatives from sect. Poeltiae are phylogenetically only distantly related, whereas members of its sister groups, namely of sect. Trabeculatae and sect. Fruticosae are morphologically conspicuously different.