Ecology and distribution ofDermatocarpon(Verrucariaceae,Ascomycota) in the catchment areas of two Bulgarian rivers

Temperature preferences and small-scale distribution patterns of fourDermatocarpontaxa in the catchment areas of two Bulgarian rivers were analyzed. Taxa with an overall alpine or arctic-alpine distribution were restricted to microhabitats with the lowest water and rock surface temperatures. A trend for increasingDermatocarpon rivulorumthallus diameter and colony size (aggregates of thalli) with decreasing temperature was identified. Data on pH and conductivity of the water for the study sites are provided for all taxa.Dermatocarpon arnoldianumis reported for the first time from Bulgaria, confirmed by ITS sequence data, and its known range extends to South-East Europe. All previous records ofD. rivulorumfrom Bulgaria were based on misidentified specimens ofD. arnoldianum. Freshwater taxa ofDermatocarponare proposed as a tool for monitoring the biological effects of temperature changes due to global climate change. Thallus and colony size are recommended as additional features for monitoring populations of threatenedDermatocarponspecies.