Published online by Cambridge University Press: 16 March 2015
Hypogymnia papilliformis McCune, Tchabanenko & X. L.Wei is described as a new species of lichenized fungus from the Primorsky region of Russia and Shaanxi Province in China. It is a relatively rare species from mixed conifer-broadleaved forests in suboceanic climates, in mountainous areas at elevations of 600–1500 m. Most similar to H. delavayi, the species are distinguished by branching pattern and chemistry. Hypogymnia papilliformis is predominantly isotomically branched while H. delavayi usually develops subpinnate branching. The ceiling of the lobe cavity is mid brown to dark brown in H. papilliformis, while the ceiling is often pale brownish or white in H. delavayi. Also, H. papilliformis lacks 3-hydroxyphysodic acid, and thus has a K– medulla, while H. delavayi always contains 3-hydroxyphysodic acid as a major substance and is thus K+ slowly reddish brown. We provide a key to the six esorediate Hypogymnia species known from the Russian Far East.