| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Acmaea mitra Rathke 1833 | 0 | 0 | 1 |
| Acmaeidae Forbes 1850 | 2 | 0 | 0 |
| Acmira | 1 | 0 | 0 |
| Aricidea (Acmira) lopezi Berkeley & Berkeley 1956 | 0 | 0 | 2 |
| Acnanthales | 0 | 0 | 0 |
| Aconchulinida | 1 | 0 | 0 |
| Acrochaete | 1 | 0 | 0 |
| Ulvella ramosa | 0 | 0 | 2 |
| Acrochaetiaceae | 3 | 0 | 0 |
| Acrochaetiales | 1 | 0 | 0 |
| Acrochaetium Nägeli 1858 | 2 | 0 | 0 |
| Acrochaetium pacificum | 0 | 0 | 1 |
| Acrochaetium porphyrae | 0 | 0 | 1 |
| Acrosiphonia J. Agardh 1846 | 5 | 0 | 0 |
| Acrosiphonia arcta | 0 | 0 | 1 |
