- 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 muelleri | 108 | ||
| Achnanthes naviformis | 270 | ||
| Achnanthes taylorensis | Achnanthes taylorensis | Achnanthes brevipes var. intermedia | 7 |
| Achnanthidium minutissimum | Achnanthes minutissima | 109 | |
| Achnanthidium modestiforme | Achnanthes modestiformis | Achnanthes modesta | 271 |
| Cocconeis neothumensis | Cocconeis diminuta | 122 | |
| Eucocconeis aretasii | Achnanthes aretasii | 144 | |
| Planothidium aueri | Achnanthes pseudolanceolata, Achnanthes aueri | 241 | |
| Planothidium cyclophorum | Achnanthes cyclophora | Achnanthes lanceolata var. lanceolatoides, Achnanthes lanceolatoides, Planothidium lanceolatoide | 313 |
| Planothidium delicatulum | Achnanthes delicatula | 242 | |
| Planothidium densistriatum | 314 | ||
| Planothidium lanceolatum | Achnanthidium lanceolatum, Achnanthes lanceolata var. lanceolata | 243 | |
| Planothidium marginostriatum | 315 | ||
| Planothidium quadripunctatum | Achnanthes quadripunctata | 244 | |
| Planothidium renei | Achnanthes renei | 316 | |
| Psammothidium abundans | Achnanthes abundans, Achnanthes abundans var. elliptica | 245 | |
| Psammothidium confusiforme | 319 | ||
| Psammothidium confusum | Achnanthes confusa | 317 | |
| Psammothidium confusum var. atomoides | Achnanthes confusa var. atomoides | 318 | |
| Psammothidium germainii | Achnanthes germainii | 246 | |
| Psammothidium germainii | Achnanthes germanii | 5 | |
| Psammothidium incognitum | Achnanthes incognita | Navicula dulcis, Achnanthes stauroneioides f. striata | 320 |
| Psammothidium investians | Achnanthes investians | 247 | |
| Psammothidium levanderi | Achnanthes levanderi | 248 | |
| Psammothidium manguinii | Achnanthes manguinii | Achnanthes manguinii var. elliptica | 321 |
| Psammothidium oblongellum | Achnanthes oblongella | Achnanthes saxonica | 322 |
| Psammothidium papilio | Navicula papilio | Psammothidium chlidanos, Achnanthes childanos (p) | 4 |
| Psammothidium stauroneioides | Achnanthes stauroneioides | 249 | |
| Psammothidium subatomoides | Achnanthes subatomoides | 250 | |
| Psammothidium therezienii | Cocconeis therezienii | Achnanthes therezienii | 323 |
