Basionym Name:Helotium languidum P. Karst., [as 'langvidum'] Not. Sällsk. Fauna et Fl. Fenn. Förh., Ny Ser. 11: 235 (1870)
Homotypic synonyms:Helotium languidum (P. Karst.) Boud., Hist. Class. Discom. Eur. (Paris): 111 (1907)Helotium parile * languidum (P. Karst.) P. Karst., [as 'langvidum'] Bidr. Känn. Finl. Nat. Folk 19: 115 (1871)Helotium parile subsp. languidum (P. Karst.) P. Karst., Bidr. Känn. Finl. Nat. Folk 19: 115 (1871)