• Species: Ochrolechia turneri (Sm.) Hasselrot
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: certain

• Species: Ochrolechia upsaliensis (L.) A. Massal.
• Remark: excluded as misidentification: re-identified as Ochrolechia szatalaensis
• Fungus type: lichenized
• Treatment in Estonia: misidentification

• Species: Omphalina umbellifera (L.) Quél.
• Remark: see: Lichenomphalia umbellifera (L.) Redhead, Lutzoni, Moncalvo & Vilgalys
• Fungus type: lichenized
• Treatment in Estonia: synonym
• turba-sõlgsamblik

• Species: Opegrapha atra Pers.
• Remark: See: Arthonia atra
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Opegrapha culmigena Lib.
• Remark: see: Alyxoria culmigena (Lib.) Ertz; earlier under Opegrapha herbarum Mont.
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Opegrapha herbarum Mont.
• Remark: see: Alyxoria culmigera (Lib.) Ertz; earlier also under Opegrapha culmigena Lib.
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Opegrapha mougeotii A. Massal.
• Remark: See: Alyxoria mougeotii
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Opegrapha niveoatra (Borrer) J.R. Laundon
• Remark: earlier under Opegrapha vulgata var. subsiderella Nyl.
• Fungus type: lichenized
• Treatment in Estonia: certain

• Species: Opegrapha ochrocheila Nyl.
• Remark: See: Alyxoria ochrocheila
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Opegrapha rufescens Pers.
• Remark: See: Pseudoschismatomma rufescens
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species:
• Remark:
• Fungus type:
• Treatment in Estonia: