- Valve is organized around a line (bilateral symmetry)
- Raphe system present on one valve
- Heterovalvar
Note: The specimen(s) pictured to the right are not from Antarctica, excepting Naviculoid example.
| Taxon Name | Basionym | synonyms | ID |
|---|---|---|---|
| Achnanthes sp. #1 (angular) | 2 | ||
| Achnanthes taylorensis | Achnanthes taylorensis | Achnanthes brevipes var. intermedia | 7 |
| Psammothidium chlidanos | Achnanthes chlidanos | Achnanthes chlidanos | 4 |
| Psammothidium germainii | Achnanthes germanii | 5 |
