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Nuclearia sp Nikko.jpg
Nuclearia thermophila
Scientific classification e
Class: Cristidiscoidea
(unranked): Discicristoidea
Order: Nucleariida

Nucleariida is a group of amoebae[1] with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially similar vampyrellids mainly by having mitochondria with discoid cristae.


Nucleariids are opisthokonts,[2] the group which includes animals, fungi and several smaller groups. Several studies place the nucleariids as a sister group to the fungi.[3][4]

The genera Rabdiophrys, Pinaciophora, and Pompholyxophrys, freshwater forms with hollow siliceous scales or spines, were formerly included in Nucleariida, but are now placed in Rhizaria.[5] In the past, nucleariids were included among the heliozoa as the Rotosphaerida.

According to a 2009 paper, Fonticula, a cellular slime mold, is an opisthokont and more closely related to Nuclearia than to fungi.[6]


Nucleariids (Nuclearia[2] and Micronuclearia) are usually small, up to about 50 μm in size.


  1. ^ Zettler; Nerad, T.; O'Kelly, C.; Sogin, M. (May 2001). "The nucleariid amoebae: more protists at the animal-fungal boundary". The Journal of Eukaryotic Microbiology. 48 (3): 293–297. doi:10.1111/j.1550-7408.2001.tb00317.x. PMID 11411837.
  2. ^ a b Yoshida M, Nakayama T, Inouye I (January 2009). "Nuclearia thermophila sp. nov. (Nucleariidae), a new nucleariid species isolated from Yunoko Lake in Nikko (Japan)". European Journal of Protistology. 45 (2): 147–155. doi:10.1016/j.ejop.2008.09.004. PMID 19157810.
  3. ^ Steenkamp, E.T.; Wright, J.; Baldauf, S.L. (January 2006). "The Protistan Origins of Animals and Fungi". Molecular Biology and Evolution. 23 (1): 93–106. doi:10.1093/molbev/msj011. PMID 16151185.
  4. ^ Shalchian-Tabrizi K, Minge MA, Espelund M, et al. (7 May 2008). Aramayo R, ed. "Multigene phylogeny of choanozoa and the origin of animals". PLoS ONE. 3 (5): e2098. Bibcode:2008PLoSO...3.2098S. doi:10.1371/journal.pone.0002098. PMC 2346548. PMID 18461162.
  5. ^ Cavalier-Smith, Thomas; Chao, Ema E. (July 2012). "Oxnerella micra sp. n. (Oxnerellidae fam. n.), a Tiny Naked Centrohelid, and the Diversity and Evolution of Heliozoa". Protist. 163 (4): 574–601. doi:10.1016/j.protis.2011.12.005. PMID 22317961.
  6. ^ Matthew W. Brown, Frederick W. Spiegel and Jeffrey D. Silberman (December 2009). "Phylogeny of the "Forgotten" Cellular Slime Mold, Fonticula alba, Reveals a Key Evolutionary Branch within Opisthokonta". Molecular Biology and Evolution. 26 (12): 2699–2709. doi:10.1093/molbev/msp185. PMID 19692665.