The Nucleariid Amoebae: More Protists at the Animal‐Fungal Boundary

Abstract

ABSTRACT. 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 choanofiagellate‐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.