Synonymy:
Lichen tenuissimus Dicks., Fasc. pl. crypt. Brit. (London) 1: 12 (1785)
Collema tenuissimum (Dicks.) Hoffm., Deutschl. Fl., Zweiter Theil (Erlangen): 103 (1796) [1795]
Parmelia tenuissima (Dicks.) Ach., Methodus qua omnes detectos Lichenes Secundum Organa Carpomorpha ad Genera, Species et Varietates Redigere atque Observationibus Illustrare Tentavit Erik Acharius: 244 (1803)
Polychidium tenuissimum (Dicks.) Gray, Nat. Arr. Brit. Pl. (London) 1: 401 (1821)
Patellaria tremelloides var. tenuissima (Dicks.) Wallr., Fl. crypt. Germ. (Norimbergae) 1: 434 (1831)
Leptogium tenuissimum (Dicks.) Körb., Corpus Fl. Prov. Suec. 1: 293 (1835)
Leptogium lacerum * tenuissimum (Dicks.) Fr., Fl. Scan.: 293 (1836) [1835]
Parmelia atrocaerulea var. tenuissima (Dicks.) Schaer., Lich. helv. spicil. 11: 519 (1842)
Leptogium lacerum var. tenuissimum (Dicks.) Fr., Summa veg. Scand., Sectio Prior (Stockholm): 122 (1845)
Collema atrocaeruleum var. tenuissimum (Dicks.) Rabenh., Deutschl. Krypt.-Fl. (Leipzig) 2(1): 49 (1845)
Leptogium lacerum f. tenuissimum (Dicks.) Nyl., Not. Sällsk. Fauna et Fl. Fenn. Förh. 2: 181 (1852)
Leptogium atrocaeruleum f. tenuissimum (Dicks.) Bosch, Prodr. fl. Batav., Fungi: 168 (1853)
Parmelia pubescens f. tenuissima (Dicks.) Zahlbr., Cat. Lich. Univers. 6: 111 (1929) [1930]

Leptogium humosum Nyl., Not. Sällsk. Fauna et Fl. Fenn. Förh., Ny Ser. 4(no. 1): 8 (1858) [1858-59]
Polychidium humosum (Nyl.) Trevis., Rc. Ist. Lomb., Milano, ser. 2 13: 74 (1880)

Position in classification:
Scytinium, Collemataceae, Peltigerales, Lecanoromycetidae, Lecanoromycetes, Ascomycota, Fungi

Note:
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