| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Acanthosphaera Lemmermann 1899 | 0 | 0 | 1 |
| Acaryochloridaceae | 0 | 0 | 1 |
| Achoma brachiatum | 0 | 0 | 1 |
| Acidothermaceae | 0 | 0 | 2 |
| Acramoeba dendroida | 0 | 0 | 1 |
| Acrasidae | 0 | 0 | 1 |
| Acrosiphonia J. Agardh 1846 | 0 | 0 | 2 |
| Actidesmium Reinsch 1875 | 0 | 0 | 2 |
| Actinastrum Lagerheim 1882 | 0 | 0 | 2 |
| Actinolophus Schulze 1874 | 0 | 0 | 1 |
| Actinopolysporaceae | 0 | 0 | 2 |
| Aeronemum J. W. Snow 1912 | 0 | 0 | 1 |
| Alvikia littoralis | 0 | 0 | 1 |
| Amphimonas Dujardin 1841 | 0 | 0 | 1 |
| Amylophagus Scherffel 1925 | 0 | 0 | 1 |
