Nucleariidae

Diagnosis: Amoebae with filose pseudopodia, but segregated from other amoebae with thin pseudopodia on the basis of ultrastructural characteristics, principally the presence of discoidal or flattened mitochondrial cristae (Page and Siemensma, 1991; Patterson et al., 1987). Referred to as the nucleariid filose amoebae or as the Cristidiscoidea. The amoebae consume bacteria, detritus, algae (some penetrating the cells of healthy algae). The pseudopodia lack microtubules but are probably supported by actin microfilaments. The pseudopodia tend to project more from one face of the cell than others. With or without perforated siliceous structures adhering to the body surface.
The organisms placed in this group have previously been assigned to the Heliozoa, but they are not closely related to that group. They have fine filopodia which lack however the internally support of axonemes and the presence of extrusomes, which are key-characteristics for the true Heliozoa.
Mostly reported from freshwater locations. Widespread in distribution but not necessarily common.