Sibling Taxa
- Amphoropsis
- Archaegladiopsophycidae
- Aulacoseirales
- Bacillariophycidae
- Belonastrum
- Biddulphiophycidae
- Chaetocerotophycidae
- Corethrophycidae
- Coscinodiscophycidae
- Cymatosirophycidae
- Eunotiophycidae
- Fragilariophycidae
- Himantidium
- Hobaniella
- Lacustriella
- Mediopyxis
- Melosirophycidae
- Navigeia
- Paraliophycidae
- Pennales
- Phaeodactylaceae
- Placogeia
- Playaensis
- Pseudopyxilla
- Ralfsiella
- Rhizosoleniales
- Thalassiosirophycidae
- Triceratiales
- Urneidophycidae