Nucleariid
The
nucleariids are a small group of
amoeboid protits with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the similar
vampyrellids mainly by having
mitochondria with discoid cristae. Genetic studies place them near the
animals and
fungi.
Nucleariids are usually small, up to about 50 μm in size. Nuclearia and Vampyrellidium, which are respectively parsitic on and in algae, take the form of naked amorphous cells. The other genera, Rabdiophrys, Pinaciophora, and Pompholyxophrys, are freshwater forms with hollow siliceous scales or spines. These were formerly included among the heliozoa as the Rotosphaerida.