Umbilicaria freyi – a new lichen species for Russia and other noteworthy records of Umbilicaria from the Elbrus region (Central Caucasus, Kabardino-Balcaria)

An annotated list of 15 species of Umbilicaria Hoffm. collected in Elbrus region (Central Caucasus, Kabardino-Balcaria) is presented. The description and a localities of a new to Russia and Bulgaria lichen species Umbilicaria freyi Codogno et al. are reported. The species is characterized by developing of shizidia as vegetative propagules. Umbilicaria aprina Nyl., U. freyi, U. lyngei Schol. and U. maculata Krzewicka et al. are reported for the Caucasus Mountains for the first time, U. altaiensis Wei et Jiang, U. cinerascens (Arnold) Frey и U. sub­glabra (Nyl.) Harm. are new for the Central Caucasus. Outside Caucasus U. altaiensis Wei et Jiang is new for Austria, U. freyi – new for Bulgaria, and U. maculata – new for Altai Mts.