| Geltingia groenlandiae Alstrup & D. Hawksw. = Unguiculariopsis groenlandiae |
| Girardia atrovirens (Dillwyn) Gray = Ephebe lanata |
| Gloeolecta bryophaga ( ex Arnold) Vzda = Bryophagus gloeocapsa |
| Gloeopeziza crozalsii sensu Dennis = Vezdaea retigera |
| Gloniopsis watsonii Rilstone = Graphina ruiziana |
| Glyphis labyrinthica = Syncesia myrticola |
| Gongylia incarnata (Th. Fr.) Zahlbr. = Belonia incarnata |
| Gongylia sabuletorum (Fr.) Stein = Arthrorhaphis grisea |
| Gongylia viridis A.L. Sm. = Arthrorhaphis grisea |
| Gonionema compactum (Agardh) Nyl. = non-lichenized Scytonema sp. {cyanobacterium} |
| Gonionema velutinum (Ach.) Nyl. = Thermutis velutina |
| Graphina anguina var. pulverulenta sensu A.L. Sm. = Graphina anguina europ. |
| Graphina inustula (Nyl.) A.L. Sm. = Graphina anguina europ. |
| Graphina ruiziana var. anomala (Leight.) Zahlbr. = Graphina ruiziana |
| Graphis britannica Staiger = Graphina anguina europ. |
| Graphis dendritica (Ach.) Ach. = Phaeographis dendritica |
| Graphis dendritica var. obtusa (Leight.) Mudd = Phaeographis dendritica |
| Graphis diffracta Turner ex Leight. = Graphis scripta |
| Graphis diffracta var. flexuosa Leight. = Graphis scripta |
| Graphis diffracta var. major Leight. = Graphis scripta |
| Graphis diffracta var. minor Leight. = Graphis scripta |
| Graphis diffracta var. radiata Leight. = Graphis scripta |
| Graphis inusta = Phaeographis smithii |
| Graphis lyellii (Sm.) Ach. = Phaeographis lyellii |
| Graphis petrina Nyl. = Graphis elegans |
| Graphis pulverulenta sensu Leight., non (Pers.) Ach. = Graphina anguina europ. |
| Graphis ramificans Nyl. = Graphis elegans |
| Graphis ruiziana (Fйe) A. Massal. = Graphina ruiziana |
| Graphis scripta f. horizontalis Leight. = Graphis scripta |
| Graphis scripta f. varia Leight. = Graphis scripta |
| Graphis scripta sensu Leight. (1854) = Graphina anguina europ. |
| Graphis scripta var. diffracta (Turner ex Leight.) Mudd = Graphis scripta |
| Graphis scripta var. diffracta f. flexuosa (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. diffracta f. major (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. diffracta f. minor (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. diffracta f. radiata (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. diffusa Leight. = Graphina anguina europ. |
| Graphis scripta var. divaricata (Leight.) Mudd, non Leight. (1854) = Graphis scripta |
| Graphis scripta var. divaricata Leight. = Graphina anguina europ. |
| Graphis scripta var. eutypa (Ach.) Mudd = Graphis scripta |
| Graphis scripta var. flexuosa (Leight.) Mudd, non Leight. (1854) = Graphis scripta |
| Graphis scripta var. flexuosa Leight. = Graphina anguina europ. |
| Graphis scripta var. horizontalis (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. minuta (Leight.) Mudd, non Leight. (1854) = Graphis scripta |
| Graphis scripta var. radiata (Leight.) Mudd, non Leight. (1854) = Graphis scripta |
| Graphis scripta var. radiata Leight. = Graphina anguina europ. |
| Graphis scripta var. recta (Humb.) Mudd = Graphis scripta |
| Graphis scripta var. serpentina (Ach.) Nyl. = Graphis scriptav |
| Graphis scripta var. serpentina f. eutypa (Ach.) Leight. = Graphis scripta |
| Graphis scripta var. spathaea (Ach.) Mudd = Graphis scripta |
| Graphis scripta var. stellata (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. tremulans (Leight.) Mudd = Graphis scripta |
| Graphis scripta var. varia (Leight.) Mudd = Graphis scripta |
| Graphis serpentina (Ach.) Leight. = Graphis scripta |
| Graphis serpentina var. diffusa Leight. = Graphis scripta |
| Graphis serpentina var. divaricata Leight. = Graphis scripta |
| Graphis serpentina var. eutypa (Ach.) Leight. = Graphis scripta |
| Graphis serpentina var. flexuosa Leight. = Graphis scripta |
| Graphis serpentina var. horizontalis Leight. = Graphis scripta |
| Graphis serpentina var. minuta Leight. = Graphis scripta |
| Graphis serpentina var. radiata Leight. = Graphis scripta |
| Graphis serpentina var. recta (Humb.) Leight. = Graphis scripta |
| Graphis serpentina var. spathea (Ach.) Leight. = Graphis scripta |
| Graphis serpentina var. stellata Leight. = Graphis scripta |
| Graphis serpentina var. tremulans Leight. = Graphis scripta |
| Graphis serpentina var. varia Leight. = Graphis scripta |
| Graphis sophistica = Graphina anguina europ. |
| Graphis sophistica var. pulverulenta (Arnold) Leight. = Graphina anguina europ. |
| Guignardia corniculata (Wallr.) Keissl. = Obryzum corniculatum |
| Guignardia fimbriata = Phaeopyxis punctum |
| Guignardia olivieri (Vouaux) Sacc. = Telogalla olivieri |
| Guignardia psoromoides (Borrer) Keissl. = Catapyrenium psoromoides |
| Gyalecta ascaridiella (Nyl.) Zahlbr. = Spirographa fusisporella |
| Gyalecta bryophaga ( ex Arnold) Hellb. = Bryophagus gloeocapsa |
| Gyalecta carneolutea (Turner) H. Olivier = Cryptolechia carneolutea |
| Gyalecta cornea (Ach.) Tuck. = Pachyphiale carneola |
| Gyalecta corticola (Lцnnr.) A.L. Sm. = Pachyphiale fagicola |
| Gyalecta cupularis (Hedw.) Schaer. = Gyalecta jenensis |
| Gyalecta diluta (Pers.) Blomb. & Forssell = Dimerella pineti |
| Gyalecta exanthematica (Sm.) Fr. = Petractis clausa |
| Gyalecta fritzei Stein = Gyalidea fritzei |
| Gyalecta gloeocapsa (Nitschke ex Arnold) Zahlbr. = Bryophagus gloeocapsa |
| Gyalecta livida (Mudd) Zahlbr. = Megalaria laureri |
| Gyalecta lutea (Dicks.) Fr. = Dimerella lutea |
| Gyalecta roseola Arnold = Gyalidea roseola |
| Gyalecta rubra (Hoffm.) A. Massal. = Gyalecta ulmi |
| Gyalecta truncigena var. derivata (Nyl.) Boistel = Gyalecta derivata |
| Gyalectina carneolutea (Turner) Vzda = Cryptolechia carneolutea |
| Gyalidea fritzei var. rivularis (Eitner) Vzda = Gyalidea rivularis |
| Gyrophora arctica Ach. = Umbilicaria arctica (Ach.) Nyl. |
| Gyrophora cirrhosa (Hoffm.) Vain. = Umbilicaria vellea (L.) Hoffm. |
| Gyrophora cirrhosa, non (Hoffm) Vain. = Umbilicaria crustulosa |
| Gyrophora cirrosa = Umbilicaria crustulosa |
| Gyrophora cylindrica (L.) Ach. = Umbilicaria cylindrica |
| Gyrophora cylindrica f. denticulata (Ach.) Mudd = Umbilicaria cylindrica |
| Gyrophora cylindrica f. denudata (Turner & Borrer) Mudd = Umbilicaria cylindrica |
| Gyrophora cylindrica f. exasperata (Turner & Borrer) Mudd = Umbilicaria cylindrica |
| Gyrophora cylindrica f. fimbriata (Ach.) Cromb. = Umbilicaria cylindrica |
| Gyrophora cylindrica var. delisei (Nyl.) Th. Fr. = Umbilicaria cylindrica |
| Gyrophora cylindrica var. denticulata Ach. = Umbilicaria cylindrica |
| Gyrophora cylindrica var. fimbriata Ach. = Umbilicaria cylindrica |
| Gyrophora cylindrica var. tornata (Ach.) Th. Fr. = Umbilicaria cylindrica |
| Gyrophora decussata (Vill.) Zahlbr. = Umbilicaria decussata (Vill.) Zahlbr. |
| Gyrophora deusta (L.) Ach. = Umbilicaria deusta |
| Gyrophora deusta var. corrugata (Hoffm.) Turner & Borrer = Umbilicaria proboscidea |
| Gyrophora deusta var. fimbriata Turner & Borrer = Umbilicaria proboscidea |
| Gyrophora deusta var. mesenteriformis sensu Turner & Borrer, non (Wulfen) Turner
& Borrer = Umbilicaria proboscidea |
| Gyrophora erosa (Weber) Ach. = Umbilicaria torrefacta |
| Gyrophora flocculosa (Wulfen) Turner & Borrer = Umbilicaria deusta |
| Gyrophora glabra (Ach.) Ach. = Umbilicaria polyphylla |
| Gyrophora glabra var. polyphylla (L.) Gray = Umbilicaria polyphylla |
| Gyrophora grisea (Hoffm.) Turner & Borrer = Umbilicaria grisea |
| Gyrophora hyperborea (Ach.) Ach. = Umbilicaria hyperborea |
| Gyrophora hyperborea var. arctica (Ach.) Mudd = Umbilicaria arctica (Ach.) Nyl. |
| Gyrophora leiocarpa = Umbilicaria rigida (Du Rietz) Frey |
| Gyrophora pellita (Ach.) Ach. = Umbilicaria polyrrhiza |
| Gyrophora polyphylla (L.) Funk = Umbilicaria polyphylla |
| Gyrophora polyphylla f. glabra (Ach.) Th. Fr. = Umbilicaria polyphylla |
| Gyrophora polyphylla f. lacera (Leight.) Hepp = Umbilicaria polyphylla |
| Gyrophora polyphylla var. congregata Turner & Borrer = Umbilicaria polyphylla |
| Gyrophora polyphylla var. flocculosa (Wulfen) Hepp = Umbilicaria deusta |
| Gyrophora polyphylla var. sulcata Turner & Borrer = Umbilicaria polyphylla |
| Gyrophora polyrrhiza (L.) = Umbilicaria polyrrhiza |
| Gyrophora polyrrhiza f. luxurians (Ach.) Th. Fr. = Umbilicaria polyrrhiza |
| Gyrophora proboscidea (L.) Ach. = Umbilicaria proboscidea |
| Gyrophora proboscidea f. exasperata (Hoffm.) Cromb. = Umbilicaria proboscidea |
| Gyrophora proboscidea f. fimbriata (Turner & Borrer) Mudd = Umbilicaria
proboscidea |
| Gyrophora proboscidea sensu Turner & Borrer, non (L.) Ach. = Umbilicaria
cylindrica |
| Gyrophora proboscidea var. arctica (Ach.) Wahlenb. = Umbilicaria arctica (Ach.) Nyl. |
| Gyrophora proboscidea var. denticulata (Ach.) Turner & Borrer = Umbilicaria
cylindrica |
| Gyrophora proboscidea var. denudata Turner & Borrer = Umbilicaria cylindrica |
| Gyrophora proboscidea var. exasperata Turner & Borrer = Umbilicaria cylindrica |
| Gyrophora pustulata (L.) Ach. = Lasallia pustulata |
| Gyrophora spodochroa = Umbilicaria crustulosa |
| Gyrophora stipitata (Nyl.) Branth. = Umbilicaria virginis Schaer. |
| Gyrophora torrefacta (Lightf.) Cromb. = Umbilicaria torrefacta |
