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 |
|---|---|---|---|---|---|---|---|---|---|---|
| 4501 | Lecidea tenebricosa | auct. brit. p.p. | No | Japewiella tavaresiana | 708 | LC | ||||
| 4502 | Lecidea tenebricosa | auct. brit. p.p. | No | Lecidea erythrophaea | 720 | VU B NR P Eng Sc | ||||
| 4503 | Lecidea tenebricosa | No | 1550 | BLS number no longer used | ||||||
| 4504 | Lecidea tenebrosa | Flot. | No | Schaereria fuscocinerea var. fuscocinerea | 1313 | LC | ||||
| 4505 | Lecidea tenera | Nyl. | No | Cliostomum tenerum | 689 | LC | ||||
| 4506 | Lecidea tephrizans | Leight. (1878) | No | Leimonis erratica | 719 | LC | ||||
| 4507 | Lecidea thriptophylla | Ach. (1808) | No | Parmeliella thriptophylla | 1032 | LC Sc L IR | ||||
| 4508 | Lecidea tornoënsis | Nyl. | No | Japewia tornoënsis | 786 | VU D2 NR Sc | ||||
| 4509 | Lecidea tornoënsis | Nyl. | No | Japewia tornoensis | 786 | orth. var. | VU D2 NR Sc | |||
| 4510 | Lecidea tricolor | Nyl. | No | Cliostomum griffithii | 429 | LC | ||||
| 4511 | Lecidea triphragmia | Nyl. | No | Buellia geophila | Buellia geophila (Flörke ex Sommerf.) Lynge, incorrectly reported from the British Isles | |||||
| 4512 | Lecidea trochodes | (Taylor ex Leight.) Cromb. | No | Rimularia limborina | 741 | LC NS | ||||
| 4513 | Lecidea truncigena | (Ach.) Nyl. | No | Gyalecta truncigena | 541 | LC | ||||
| 4514 | Lecidea tumida | A. Massal. | No | Porpidia tuberculosa | 572 | LC | ||||
| 4515 | Lecidea tumidior | (Nyl.) Vain. | No | ? Miriquidica griseoatra | ||||||
| 4516 | Lecidea turfosa | (A. Massal.) Jatta | No | Micarea turfosa | 897 | LC NS | ||||
| 4517 | Lecidea turgidula | Fr. (1824) | Yes | Lecidea turgidula | 787 | LC | Lecidea turgidula | |||
| 4518 | Lecidea turgidula var. endopella | (Leight. ex Cromb.) Cromb. | No | Lecidea turgidula | 787 | LC | ||||
| 4519 | Lecidea turgidula var. pithyophila | (Sommerf.) Nyl. | No | Lecidea turgidula | 787 | LC | ||||
| 4520 | Lecidea turneri | Leight. (1871) | No | Toniniopsis aromatica | 1415 | LC | ||||
| 4521 | Lecidea turneriana | Ach. (1810) | No | Kuettlingeria atroflava | 237 | CR D NR P Wa | ||||
| 4522 | Lecidea uliginascens | Stirt. | No | Placynthiella hyporhoda | 1788 | LC NR | ||||
| 4523 | Lecidea uliginosa | auct. brit. p.p. | No | Placynthiella icmalea | 732 | LC | ||||
| 4524 | Lecidea uliginosa | (Schrad.) Ach. | No | Placynthiella uliginosa | 788 | LC | ||||
| 4525 | Lecidea uliginosa var. humosa | sensu Leight., non (Hoffm.) Ach. | No | Placynthiella oligotropha | 756 | LC NS | ||||
| 4526 | Lecidea ulmicola | (DC.) Borrer ex Hook. | No | Cerothallia luteoalba | 266 | EN A2, C1 NS P Eng Sc Wa S8 | ||||
| 4527 | Lecidea umbonata | auct. brit., non (Hepp) Mudd | No | Cecidonia umbonella | 789 | LC NS | LF | |||
| 4528 | Lecidea umbonella | Nyl. | No | Cecidonia umbonella | 789 | LC NS | LF | |||
| 4529 | Lecidea umbonella var. alumnula | (Nyl.) Hertel | No | Cecidonia xenophana | 1838 | LC NS | LF | |||
| 4530 | Lecidea umbrina | Ach. | No | Scoliciosporum umbrinum | 1322 | LC |