| Lithoderma Aresch., 1875 |
| Lithoderma maculiforme Wollny, 1881 |
| Petroderma Kuck., 1897 |
| Petroderma maculiforme (Wollny) Kuck., 1897 |
| Pseudolithoderma Sved., 1910 |
| Pseudolithoderma nigrum Hollenberg, 1969 |
| Ralfsia Berk., 1843 |
| Ralfsia californica Setch. & N.L. Gardner, 1924 |
| Ralfsia confusa Hollenberg, 1969 |
| Ralfsia expansa (J. Agardh) J. Agardh, 1848 |
| Ralfsia fungiformis (Gunnerus) Setch. & N.L. Gardner, 1924 |
| Ralfsia hancockii E.Y. Dawson, 1944 |
| Ralfsia hesperia Setch. & N.L. Gardner, 1924 |
| Ralfsia integra Hollenberg, 1969 |
| Ralfsia occidentalis Hollenberg, 1945 |
| Ralfsia pacifica Hollenberg, 1944 |
| Ralfsia pangoensis Setch., 1924 |
| Ralfsia verrucosa (Aresch.) Aresch., 1845 |
| Ralfsiaceae Farlow, 1881 |