| Ocellularia subtilis (Tuck.) Riddle = Thelotrema subtile Tuck. |
| Ocellularia subtilis, non (Tuck.) Riddle = Thelotrema petractoides |
| Ochrolechia frigida f. lapuensis (Vain.) Coppins = Ochrolechia frigida |
| Ochrolechia geminipara (Th. Fr.) Vain. = Pertusaria geminipara |
| Ochrolechia pallescens = Ochrolechia parella |
| Ochrolechia pallescens = Ochrolechia szatalaensis |
| Ochrolechia parella var. turneri (Sm.) de Lesd. = Ochrolechia turneri |
| Ochrolechia upsaliensis (L.) A. Massal. = Ochrolechia yasudae = Ochrolechia subviridis |
| Omphalina alpina (Britzelm.) Bresinsky & Stangl = Lichenomphalia alpina |
| Omphalina cupulatoides P.D. Orton = Arrhenia peltigerina [LF] |
| Omphalina ericetorum (Pers.:Fr.) M. Lange ex H.E. Bigelow = Lichenomphalia umbellifera |
| Omphalina fulvopallens P.D. Orton = Lichenomphalia umbellifera |
| Omphalina grisella (Weinm.) M.M. Moser = Lichenomphalia velutina |
| Omphalina griseopallida (Desm.) Quйl. = Arrhenia griseopallida (Desm.) Watling |
| Omphalina hudsoniana (H.S. Jenn.) H.E. Bigelow = Lichenomphalia hudsoniana |
| Omphalina luteolilacina (Favre) D.M. Hend. = Lichenomphalia hudsoniana |
| Omphalina luteovitellina (Pilбt & Nannf.) M. Lange = Lichenomphalia alpina |
| Omphalina pararustica Clйmenзon = Lichenomphalia velutina |
| Omphalina peltigerina (Peck) P. Collin = Arrhenia peltigerina |
| Omphalina pseudoandrosacea (Bull.) M.M. Moser = Lichenomphalia umbellifera |
| Omphalina umbellifera (L.:Fr.) Quйl. = Lichenomphalia umbellifera |
| Omphalina velutina (Quйl.) Quйl. = Lichenomphalia velutina |
| Opegrapha “sp. A” sensu D. Hawksw. (1983) = Opegrapha brevis |
| Opegrapha “sp. B” sensu D. Hawksw. (1983) = Opegrapha thelotrematis |
| Opegrapha abscondita Th. Fr. = Lecanographa abscondita |
| Opegrapha actophila Nyl. = Opegrapha areniseda |
| Opegrapha anomala Leight. = Graphina ruiziana |
| Opegrapha atra f. tenuior Nyl. ex Leight. = Opegrapha atra |
| Opegrapha atra var. arthonioidea Leight. = Opegrapha atra |
| Opegrapha atra var. denigrata (Ach.) Schaer. = Opegrapha atra |
| Opegrapha atra var. nigrata Leight. ex Mudd = Opegrapha atra |
| Opegrapha atra var. parallela Leight. ex Mudd = Opegrapha atra |
| Opegrapha atricolor Stirt. = Opegrapha ochrocheila |
| Opegrapha atrula Nyl. = Opegrapha calcarea |
| Opegrapha betulina Sm., non Pers. = Opegrapha herbarum |
| Opegrapha calcarea var. chevallieri (Leight.) H. Olivier = Opegrapha calcarea |
| Opegrapha centrifuga A. Massal. = Opegrapha rupestris |
| Opegrapha chevallieri Leight. = Opegrapha calcarea |
| Opegrapha cinerea Chevall. = Opegrapha vulgata |
| Opegrapha conferta = Opegrapha calcarea |
| Opegrapha conferta Anzi, non = Opegrapha saxigena |
| Opegrapha confluens (Ach.) Stizenb., non = Opegrapha vulgata |
| Opegrapha confluens = Opegrapha calcarea |
| Opegrapha contexta Stirt. = Opegrapha rufescens |
| Opegrapha crassa DC. = Enterographa crassa |
| Opegrapha culmigena Lib. = Opegrapha herbarum |
| Opegrapha decandollei (Stizenb.) Arnold = Opegrapha calcarea |
| Opegrapha dendritica Ach. = Phaeographis dendritica |
| Opegrapha devulgata Nyl. = Opegrapha vulgata |
| Opegrapha diaphora (Ach.) Ach. = Opegrapha varia |
| Opegrapha dubia Leight. ex Arnold = Opegrapha niveoatra |
| Opegrapha elegans Borrer ex Sm. = Graphis elegans |
| Opegrapha grumulosa Dufour = Lecanographa grumulosa |
| Opegrapha herpetica (Ach.) Ach. = Opegrapha rufescens |
| Opegrapha horistica (Leight.) Stein = Opegrapha zonata |
| Opegrapha hutchinsiae (Leight.) = Enterographa hutchinsiae |
| Opegrapha hysteriiformis Nyl. = Opegrapha cesareensis |
| Opegrapha involuta (Wallr.) Jatta = Opegrapha viridis |
| Opegrapha leightonii Cromb. ex Nyl. = Opegrapha mougeotii |
| Opegrapha lentiginosa Lyell ex Leight. = Melaspilea lentiginosa |
| Opegrapha lichenoides Pers. = Opegrapha varia |
| Opegrapha lithyrgodes Nyl. = Opegrapha lithyrga |
| Opegrapha lyellii Sm. = Phaeographis lyellii |
| Opegrapha lyncea (Sm.) Borrer ex Hook. = Lecanographa lyncea |
| Opegrapha microscopica Sm. = Arthonia punctiformis |
| Opegrapha monspeliensis Nyl. = Opegrapha parasitica |
| Opegrapha multipunctata Coppins & P. James ad int. = Opegrapha multipuncta |
| Opegrapha nothiza Nyl. = Lecanographa grumulosa |
| Opegrapha parasitica p.min.p. [on Xanthoria parietina] = Opegrapha physciaria |
| Opegrapha parasitica pre-1995 [on endolithic Verrucariaceae] = Opegrapha rupestris |
| Opegrapha persoonii (Ach.) Chevall., nom. illeg. = Opegrapha rupestris |
| Opegrapha prosiliens Stirt., non Mont. & Bosch = Opegrapha herbarum |
| Opegrapha protuberans Zahlbr. = Opegrapha herbarum |
| Opegrapha pseudovaria Coppins ad int. = Opegrapha xerica |
| Opegrapha pulicaris = Opegrapha varia |
| Opegrapha pulverulenta Sm., non Pers. = Graphina anguina europ. |
| Opegrapha rimalis Ach. = Opegrapha varia |
| Opegrapha rubella p.max.p. = Opegrapha rufescens |
| Opegrapha rubella sensu Mudd = Opegrapha viridis |
| Opegrapha saxatilis DC., non = Opegrapha rupestris |
| Opegrapha saxatilis p.max.p. = Opegrapha calcarea |
| Opegrapha saxatilis sensu Leight., non DC. = Opegrapha mougeotii |
| Opegrapha saxicola = Opegrapha dolomitica |
| Opegrapha saxicola var. decandollei Stizenb. = Opegrapha calcarea |
| Opegrapha saxicola var. gyrocarpa (Flot.) Stizenb. = Opegrapha gyrocarpa |
| Opegrapha saxicola var. persoonii = Opegrapha rupestris |
| Opegrapha scripta (L.) Ach. = Graphis scripta |
| Opegrapha semicincta Zahlbr. = Opegrapha rupestris |
| Opegrapha siderella = Opegrapha vulgata |
| Opegrapha siderella Ach. = Opegrapha rufescens |
| Opegrapha subsiderella (Nyl.) Arnold = Opegrapha niveoatra |
| Opegrapha sulcata Moug. & Nestl. ex DC. = Graphis elegans |
| Opegrapha turneri Leight. = Opegrapha herbarum |
| Opegrapha varia f. pulicaris = Opegrapha varia |
| Opegrapha varia var. pulicaris = Opegrapha varia |
| Opegrapha venosa = Enterographa crassa |
| Opegrapha venosa sensu Sm. (1812), non Pers. (1811) = Enterographa elaborata |
| Opegrapha viridis f. taxicola (Leight.) Cromb. = Opegrapha prosodea |
| Opegrapha vulgaris (sphalm.) = Opegrapha vulgata |
| Opegrapha vulgata var. siderella = Opegrapha niveoatra |
| Opegrapha vulgata var. subsiderella Nyl. = Opegrapha niveoatra |
| Opegrapha xanthodes Nyl. = Opegrapha saxigena |
| Ophiobolus peltigerae (Mont.) Sacc. = Neolamya peltigerae |
| Ophioparma lapponica Hafellner & R.W. Rogers = British status of this species
doubtful |
| Orbicula tartaricola (Nyl.) Cooke = Roselliniopsis tartaricola |
| Orphniospora atrata (Sm.) Poelt = Orphniospora moriopsis |
| Orphniospora atrata var. brunnea (A.L. Sm.) Poelt = Orphniospora moriopsis var.
brunnea |
| Oxneria coppinsii (S. Kondratyuk & Kдrnefelt & Sшchting) S. Kondratyuk &
Kдrnefelt nom. inval. = Xanthoria ulophyllodes |
| Oxneria fulva (Hoffm.) S. Kondratyuk & Kдrnefelt = Xanthoria fulva |
| Oxneria ulophyllodes S. Kondratyuk & Kдrnefelt = Xanthoria ulophyllodes |
