Published online by Cambridge University Press: 18 January 2017
Four new species of Verrucaria are described from calcareous rocks in Finland based on morphology and ITS sequences. Verrucaria lapponica sp. nov. differs from V. cincta by the smaller perithecia, thinner periphysoids and occasional occurrence of pale exciple walls. Verrucaria sublapponica sp. nov. is related to V. lapponica but differs by a shorter involucrellum and larger spores. Verrucaria saanaensis sp. nov. differs from V. nuoljae (H. Magn.) comb. ined. by having larger spores and a fimbriate prothallus. Verrucaria othmarbreussii sp. nov. is closely related to V. tenebrica, but differs by the paler and thinner, less areolate thallus. The four species belong to the Staurothele group based on the BLAST search and the ITS phylogeny. All four species are rare in Finland and all except V. othmarbreussii seem to have a narrow ecogeographical niche on calcareous mountains above the tree line. Lichens restricted to these habitats may be especially sensitive to climate warming.