Most species belonging to the Extremaceae family are rock-inhabiting fungi (RIF), which have a deteriorative potential towards colonized substrate. Extremus adstrictus originally isolated from limestone formations in Mallorca is reported from a dolomite wall in Poland. It is the first non-Spanish documented occurrence of this species. Identification of the strain is supported by morphological and molecular analyses. Sequences of uncharacterized fungal cultures and environmental data are analyzed in order to verify probable distribution of Extremus adstrictus.