Rhizocarpon macrosporum is characterized by small bright yellow thalli composed of minute compact areoles on a notable black prothallus. Its spores are muriform and up to 70 µm large. In the field, it is indistinguishable from the common R. geographicum.
It is a continental species, distributed from central France and Spain to western Scandinavia. It usually grows on exposed dust-impregnated siliceous rocks, boulders or rock walls at higher elevations. In the Czech Republic, the lichen has recently been recorded in the Hřebenec nature reserve in the Brdy highlands, uranium heap piles near Příbram, Úpská jáma in the Krkonoše Mts and Velká Kotlina in the Jeseníky Mts.
Literature: Runemark H. (1956): Studies in Rhizocarpon, II. Distribution and ecology of the yellow species in Europe. – Opera Botanica 2: 1–150.taxonomic classification:
All records: 4, confirmed 4. One click on a selected square displays particular record(s), including their source(s).