For more information see the Supplementary Notes for the Taxon Dictionary, which explains the names and synonyms, and these Instructions on how to use the online Taxon Dictionary which includes details of the Conservation Evaluation codes.
| Count | Name | Authority | Is Current Name? | Current Taxon Name | Synonyms | BLS Number | Comments | Conservation Evaluation | Group | Account & Map |
|---|---|---|---|---|---|---|---|---|---|---|
| 271 | Arthonia amylospora | Almq. (1880) | Yes | Arthonia amylospora | 1930 | LC NR Sc | LF | Arthonia amylospora | ||
| 272 | Arthonia anastomosans | auct. brit. p.p. | No | Arthothelium lirellans | 1569 | LC NS Sc IR | F | |||
| 273 | Arthonia anastomosans | auct. brit. p.p. | No | Arthothelium orbilliferum | 1711 | LC NS Sc IR | F | |||
| 274 | Arthonia anglica | Coppins (1989) | Yes | Arthonia anglica | 1686 | EN B, D NR P Eng IR | Arthonia anglica | |||
| 275 | Arthonia anombrophila | Coppins & P. James (1989) | No | Reichlingia anombrophila | 1588 | LC NS Sc IR | ||||
| 276 | Arthonia apatetica | (A. Massal.) Th. Fr. (1866) | Yes | Arthonia apatetica | 2418 | DD NR Sc | Arthonia apatetica | |||
| 277 | Arthonia apotheciorum | (A. Massal.) Almq. (1880) | Yes | Arthonia apotheciorum | Arthonia clemens auct. brit. | 1501 | LC NS | LF | Arthonia apotheciorum | |
| 278 | Arthonia armoricana | Leight. non Nyl. | No | Synarthonia astroidestera | 1687 | NT NS IR | ||||
| 279 | Arthonia arthonioides | (Ach.) A.L. Sm. (1911) | Yes | Arthonia arthonioides | Arthonia aspersa | 51 | LC NS | Arthonia arthonioides | ||
| 280 | Arthonia aspersa | Leight. (1856) | No | Arthonia arthonioides | 51 | LC NS | ||||
| 281 | Arthonia aspersella | Leight. | No | Arthonia didyma | 56 | LC | ||||
| 282 | Arthonia astroidea | Ach. | No | Arthonia radiata | 69 | LC | ||||
| 283 | Arthonia astroidea var. simulans | Leight. | No | Arthonia radiata | 69 | LC | ||||
| 284 | Arthonia astroidea var. swartziana | (Ach.) Hepp | No | Arthonia radiata | 69 | LC | ||||
| 285 | Arthonia astroidestera | Nyl. (1874) | No | Synarthonia astroidestera | 1687 | NT NS IR | ||||
| 286 | Arthonia astroidestra | Nyl. [orth. error] | No | Synarthonia astroidestera | 1687 | NT NS IR | ||||
| 287 | Arthonia atlantica | P. James (1970) | No | Reichlingia dendritica | 53 | NT NR P Eng Sc Wa IR | ||||
| 288 | Arthonia atlantica var. positiva | P. James (1978) | No | Reichlingia dendritica | 53 | NT NR P Eng Sc Wa IR | ||||
| 289 | Arthonia atra | (Pers.) A. Schneid. (1898) | Yes | Arthonia atra | Opegrapha atra | 938 | LC | Arthonia atra | ||
| 290 | Arthonia atrofuscella | Nyl. | No | Arthonia didyma | 56 | LC | ||||
| 291 | Arthonia byssacea | (Weigel) Almq. (1880) | No | Inoderma byssaceum | 2604 | VU D1 NR | ||||
| 292 | Arthonia caerulescens | (Almq.) R. Sant. (2000) | Yes | Arthonia caerulescens | 2563 | LC NR | LF | Arthonia caerulescens | ||
| 293 | Arthonia calcarea | (Turner ex Sm.) Ertz & Diederich (2009) | Yes | Arthonia calcarea | Opegrapha calcarea; Opegrapha chevallieri; Opegrapha conferta auct.; Opegrapha calcarea; Opegrapha confluens auct.; Opegrapha decandollei; Opegrapha saxatilis auct. | 959 | LC | Arthonia calcarea | ||
| 294 | Arthonia cascarillae | auct. brit., non (Fée) Nyl. | No | Arthonia radiata | 69 | LC | ||||
| 295 | Arthonia cinereopruinosa | auct. brit. | No | Reichlingia anombrophila | 1588 | LC NS Sc IR | ||||
| 296 | Arthonia cinereopruinosa | Schaer. (1850) | No | 55 | incorrectly reported from the British Isles; BLS number no longer used | |||||
| 297 | Arthonia cinnabarina | (DC.) Wallr. (1831) | No | Coniocarpon cinnabarinum | 72 | LC | ||||
| 298 | Arthonia cinnabarina f. cuspidans | Nyl. (1876) | No | Coniocarpon cuspidans | 58 | LC | ||||
| 299 | Arthonia cinnabarina f. dubia | (Turner & Borrer) Leight. | No | Coniocarpon cinnabarinum | 72 | LC | ||||
| 300 | Arthonia cinnabarina f. microstigma | (Turner & Borrer) Leight. | No | Coniocarpon cinnabarinum | 72 | LC |