Published online by Cambridge University Press: 10 March 2017
Three new species of Verrucaria are described from calcareous and calciferous rocks in Finland based on morphology and ITS sequences. The species are all members of the Endocarpon group in the Verrucariaceae. Verrucaria oulankaensis sp. nov. is related to V. cernaensis but differing in its usually pruinose, small areolate thallus. It occurs in NE Finland on calcareous and calciferous rocks on river shores. Verrucaria ahtii sp. nov. and V. vitikainenii sp. nov. form a sister group in the ITS phylogeny. Verrucaria vitikainenii differs from V. ahtii in the darker and thinner thallus, absence of a prothallus and in the perithecia, which lack thalline cover. Verrucaria ahtii morphologically resembles V. apomelaena but differs in having a thinner involucrellum and a fimbriate prothallus. It has a southern distribution in Finland and prefers sun-exposed sites, particularly pebbles in lime quarries. The species is also reported from Lithuania and Russia. Verrucaria vitikainenii has an eastern distribution in Finland. The species is a strict calcicole, preferring half-shady habitats. Verrucaria apomelaena is excluded from the Finnish lichen flora.