The thallus of R. distinctum is dull, pale brown to grey, the black apothecia are almost round without a proper margin. Epithecium is K+ purple in a microscope slide. Spores are hyaline, 3-septate to submuriform. It is distinguished by an amyloid (I+ blue) medulla.
The species grows on slightly calcareous, nutrient-enriched or dusty silicates. It is common on various anthropogenic substrates, such as walls of natural rocks, bricks, roof tiles, granite gravestones, rock monuments or menhirs. It has a wide altitudinal amplitude. In the Czech Republic, it is one of the most common and abundant brown Rhizocarpon species.taxonomic classification:
All records: 136, confirmed 120. One click on a selected square displays particular record(s), including their source(s).