Nové druhy žluté skupiny rodu Rhizocarpon v České Republice

Three species of map lichens, Rhizocarpon atroflavescens, R. carpaticum and R. ferax, have newly been discovered in the Czech Republic. These taxa occur predominantly in mountain regions with uncovered rocky outcrops and boulders. Rhizocarpon atroflavescens has a whitish prothallus and ascospores containing at most one longitudinal septum. It grows on slightly calcareous rocks. The acidophilous species Rhizocarpon carpaticum also rarely has one longitudinal septum however, the species has convex apothecia extending up above the areoles and the thallus margin is bordered with a black prothallus. Rhizocarpon ferax occurs mainly on overhangs or at bases of vertical faces of acidic rocks. It has muriform spores and its roundish apothecia are usually hidden between two crescent-shaped areoles.