<i>Ulota langxianensis</i> Qinghua Wang &amp; Y.Jia (Orthotrichaceae), a new high-altitude moss species from China

Worldwide, few species of <i>Ulota</i> are known from high-altitude regions (above 3000 m), and all these are in China or Papua New Guinea. In this article, we describe <i>U. langxianensis</i> Qinghua Wang &amp; Y.Jia, a new species from the high-altitude region of Xizang (Tibet) in China. The morphology of the new taxon was observed, measured, photographed and analysed using light microscopy. Phylogenetic inferences based on 78 concatenated plastid genes were made using maximum likelihood analyses. <i>Ulota langxianensis</i> is distinguished from other <i>Ulota</i> species by the long and smooth exostome teeth that are not united in pairs, large multicellular spores, weakly differentiated hyaline marginal cells at leaf base, and sparsely hairy calyptrae. Molecular phylogenetic analysis resolves <i>U. langxianensis</i> as sister to <i>U. yunnanensis</i> F.Lara, Caparrós &amp; Garilleti. Gametophytically, <i>U. langxianensis</i> is similar to both <i>U. yunnanensis</i> and <i>U. gigantospora</i> F.Lara, Caparrós &amp; Garilleti. Sporophytically it more closely resembles <i>U. yakushimensis</i> Z.Iwats. in having a single peristome and short exserted capsules, although all four species have multicellular spores. <i>Ulota langxianensis</i> is described in detail, along with information on its ecology and geographical distribution.