• Species: Thelomma ocellatum (Körb.) Tibell
• Remark: see: Pseudothelomma ocellatum
• Fungus type: lichenized
• Treatment in Estonia: synonym

• Species: Thelopsis flaveola Arnold
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: certain

• Species: Thelotrema lepadinum (Ach.) Ach.
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: certain
• harilik koobassamblik

• Species: Thelotrema suecicum (H. Magn.) P. James
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: certain

• Species: Thrombium epigaeum (Pers.) Wallr.
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: doubtful

• Species: Toninia physaroides (Opiz) Zahlbr.
• Remark: see: Thalloidima physaroides
• Fungus type: lichenized
• Treatment in Estonia: synonym
• sammas-nappsamblik

• Species: Toninia sedifolia (Scop.) Timdal
• Remark: see: Thalloidima sedifolium
• Fungus type: lichenized
• Treatment in Estonia: synonym
• sinakas nappsamblik

• Species: Toninia verrucarioides (Nyl.) Timdal
• Remark: see: Toniniopsis verrucarioides
• Fungus type: lichenized
• Treatment in Estonia: synonym
• pruunikas nappsamblik

• Species: Trapelia coarctata (Sm.) M. Choisy
• Remark:
• Fungus type: lichenized
• Treatment in Estonia: certain

• Species: Trapelia glebulosa (Sm.) J.R. Laundon
• Remark: earlier under Trapelia involuta (Taylor) Hertel
• Fungus type: lichenized
• Treatment in Estonia: certain

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