The nucleariid amoebae: more protists at the animal-fungal boundary. 
Nucleariid amoebae are naked amoebae, generally characterized by a spherical or sometimes flattened body with radiating filopodia.  Most species preferentially consume algal prey or cyanobacteria.  Phylogenetic analyses of the small-subunit rRNA coding regions from four nucleariid amoebae place these species near the origin of the animal-fungal divergence, together with the choanoflagellate-Corallochytrium and the ichthyosporean clades.  The species Nuclearia delicatula, N. moebiusi, and N. simplex form a monophyletic group, while ATCC 30864, tentatively but possibly incorrectly assigned to Nuclearia sp.,  represents a separate line of descent.  These nucleariids are unrelated to the lineage containing the testate filose amoebae (Testaceafilosia).  Our findings expand the morphological and phylogenetic diversity of protists at the animal-fungal divergence.