| Lacellina graminicola (Berk. & Broome) Petch, 1924 |
| Lauriomyces R. F. Castañeda, 1990 |
| Lauriomyces bellulus Crous & M. J. Wingf., 1994 |
| Lauriomyces heliocephalus (V. Rao & de Hoog) R. F. Castañeda & W. B. Kendr., 1990 |
| Lauriomyces sakaeratensis Somrith., Kosol & E.B.G. Jones, 2006 |
| Lemmermannia Chodat, 1900 |
| Lemmermannia tetrapedia (Kirchner) Lemmerm., 1904 |
| Lepidostroma Mägd. & S. Winkl., 1967 |
| Lepidostroma vilgalysii B.P. Hodk., 2012 |
| Lepidostroma winklerianum B.P. Hodk. & Lücking, 2014 |
| Leprocaulon Nyl., 1878 |
| Leprocaulon microscopicum (Vill.) Gams ex D. Hawksw., 1974 |
| Leprocaulon quisquiliare (Leers) M. Choisy, 1950 |
| Leptospora Rabenh., 1857 |
| Leptospora rubella (Pers.) Rabenh., 1857 |
| Lichenodiplis Dyko & D. Hawksw., 1979 |
| Lichenodiplis lecanorae (Vouaux) Dyko & D. Hawksw., 1979 |
| Lineolata Kohlm. & Volkm.-Kohlm., 1990 |
| Lineolata rhizophorae (Kohlm. & E. Kohlm.) Kohlm. & Volkm.-Kohlm., 1990 |
| Listeromyces Penz. & Sacc., 1902 |