Umbilicaria orientalis – a new species of Umbilicaria subg. Papillophora with an East Asian distribution: morphological delimitation and molecular evidence.

Umbilicaria orientalis Davydov sp. nov. is described and phylogenetic analysis (ITS, mtLSU and RPB2) confirmed its distinctness and indicated a sister relationship with U. trabeculata within the U. vellea group. The species is morphologically similar to U. vellea but differs by simple, cylindrical or strap-like rhizinomorphs and by thalloconidia, developing both on the lower surface and on rhizinomorphs, that are 1–2 (rarely 4)–celled or in aggregates of up to 5–6 cells. Umbilicaria orientalis is described from the Russian Far East and is currently known from a wide range of localities in East Asia, from the Far East to South Siberia and Mongolia in the north, to Hebei and Tibet in the south. New sequences of U. americana were obtained; the species represents an independent phylogenetic lineage within Umbilicaria subg. Papillophora. Diagnostic traits and variability of different developmental stages of U. orientalis, as well as its East Asian distribution pattern, are discussed. [ABSTRACT FROM AUTHOR]