Family Vannellidae Bovee, 1970
Diagnosis: Amoebae have locomotive forms markedly flattened, fan-shaped, or linguiform with a prominent anterior hyaline zone without subpseudopodia. No posterior uroid. Floating form of most with radiating pseudopodia, either blunt or tapered. Nucleus of most with prominent central nucleolus, rarely with parietal lobes. Cytoplasmic crystals rare.
Glycocalyx of the only two genera studied by TEM differentiated into either pentagonal glycostyles (Vannella) or hexagonal arrangements (Platyamoeba).
Remarks: Family diagnosis emended by Page (1987) on the basis of this ultrastructural information. The present grouping of genera is based on morphological similarities at the LM level since ultrastructural details are unavailable for most.
| 1 | Hyaloplasm smooth | 2 |
| – | Hyaloplasm with surface features | 3 |
| 2 | Hyaloplasm extends posteriorly as border | Discamoeba |
| – | Hyaloplasm predominantly anterior | Vannella |
| 3 | Surface features faint | 4 |
| – | Surface features obvious | 5 |
| 4 | Usually with faint longitudinal edge ridges | Platyamoeba |
| – | Usually with faint lateral folds | Clydonella |
| 5 | Hyaloplasm with series of superimposed waves | Unda |
| – | Hyaloplasm with conoidal bosses | Pessonella |