Basionym Name:Rhizocarpon reductum Th. Fr., Lich. Scand. (Upsaliae)(2): 633 (1874)
Homotypic synonyms:Rhizocarpon obscuratum f. reductum (Th. Fr.) Schade, Sber. Abhandl. Naturwiss. Ges. Isis: 158 (1935)Rhizocarpon obscuratum var. reductum (Th. Fr.) Eitner, Jber. schles. Ges. vaterl. Kultur 88(2b Abth.): 45 (1911)