Lichens listed under Section 42 of the Natural Environment & Rural Communities (NERC) Act 2006. Species (and lichen communities) on this list are considered to be of "principal importance for conservation of biological diversity in Wales"
(Where an account has been written for one of these species, the name will show as a hyperlink - click to jump to the account).
| Anaptychia ciliaris subsp. ciliaris | A lichen | Prysgwydden y coed |
| Arthonia atlantica | A lichen | Cen |
| Arthothelium dictyosporum | A lichen | Cen |
| Bacidia circumspecta | A lichen | Cen |
| Bacidia incompta | A lichen | Cen |
| Biatoridium monasteriense | A lichen | Cen |
| Blarneya hibernica | A lichen | Cen |
| Bryoria smithii | A lichen | Cen |
| Buellia hyperbolica | A lichen | Cen |
| Calicium adspersum | A lichen | Cen |
| Caloplaca atroflava | A lichen | Cen |
| Caloplaca flavorubescens | A lichen | Cen |
| Caloplaca herbidella | A lichen | Cen |
| Caloplaca lucifuga | A lichen | Cen |
| Caloplaca luteoalba | Orange-fruited elm lichen | Cen llwyfen ffrwythau oren |
| Chaenotheca phaeocephala | A lichen | Cen |
| Cladonia peziziformis | A lichen | Cen |
| Collema dichotomum | River jelly-lichen | Cen Gwymonaidd yr afon |
| Collema fasciculare | A lichen | Cen |
| Collema fragile | A lichen | Cen |
| Collema fragrans | A lichen | Cen |
| Endocarpon adscendens | A lichen | Cen |
| Fulgensia fulgens | Scrambled egg lichen | Wygen y twyni |
| Fuscopannaria sampaiana | A lichen | Cen |
| Gomphillus calycioides | A lichen | Cen |
| Graphina pauciloculata | A lichen | Cen |
| Gyalecta flotowii | A lichen | Cafneddgen Flotow |
| Heterodermia leucomela | Ciliate strap lichen | Cen rhuban blewog |
| Lecania chlorotiza | A lichen | Cen |
| Lecanographa amylacea | A lichen | Cen |
| Lecanora achariana | Tarn lecanora | Cen llyn mynydd |
| Lecanora quercicola | A lichen | Cen |
| Lecanora sublivescens | A lichen | Cen |
| Leptogium brebissonii | A lichen | Cen |
| Leptogium cochleatum | A lichen | Cen |
| Lobarion community | A lichen community | Cymuned o gen |
| Megalospora tuberculosa | A lichen | Cen |
| Melaspilea lentiginosa | A lichenicolous fungus | Ffwng sy'n tyfu ar gen |
| Metal-mine community | A lichen community | Cymuned o gen |
| Opegrapha prosodea | A lichen | Cen |
| Parmeliella testacea | A lichen | Cen |
| Parmelina quercina | A lichen | Cen |
| Parmelinopsis horrescens | A lichen | Cen |
| Parmotrema robustum | A lichen | Cen |
| Peltigera venosa | A lichen | Cen |
| Pertusaria velata | A lichen | Cen |
| Physcia tribacioides | Southern grey physcia | Ffisgia llwyd y de |
| Porina effilata | A lichen | Cen |
| Porina hibernica | A lichen | Cen |
| Pseudocyphellaria intricata | A lichen | Cedennog blawd lwyd |
| Pseudocyphellaria lacerata | Ragged pseudocyphellaria | Cen cedennog llarpiog |
| Pseudocyphellaria norvegica | A lichen | Cen |
| Pyrenula hibernica | A lichen | Cen |
| Pyrenula nitida | A lichen | Cen |
| Ramonia chrysophaea | A lichen | Cen |
| Ramonia dictyopsora | A lichen | Cen |
| Rinodina isidioides | A lichen | Cen |
| Schismatomma graphidioides | A lichen | Cen |
| Stereocaulon delisei | A lichen | Cen |
| Stereocaulon symphycheilum | A lichen | Cen |
| Sticta canariensis | A lichen | Pysg-gen glas |
| Strangospora microhaema | A lichen | Cen |
| Strigula stigmatella var. stigmatella | A lichen | Cen |
| Synalissa symphorea | A lichen | Cen |
| Teloschistes flavicans | Golden-hair lichen | Cen aurwallt |
| Toninia sedifolia | A lichen | Cen |
| Usnea articulata | A lichen | Brig-far flodeuog |
| Usnea florida | Witch's beard | Cen |
| Wadeana dendrographa | A lichen | Cen |