Phylum: Sarcomastigophora Honigberg & Balamuth, 1963
Subphylum: Sarcodina Hertig & Lesser, 1874
Superclass: Rhizopoda von Siebold, 1845
Class: Filosea Leidy, 1879
Filose pseudopodia, often hyaline, often branching, but not reticulate, produced from cytoplasmic mass not differentiated into distinct hyaline and granular regions; no flagellate stage known.
Order: Aconchulinida de Saedeleer, 1934
Without external skeletal material.
Familiy: Nucleariidae Cann & Page, 1979
Feeding by ingestion of food particles or by penetration of old/damaged eukaryotic algal filaments. Cross walls of filaments not observed to be attacked. Mitochondria with flattened, unbranching cristae.
Genus: Nuclearia Cienkosswski, 1865
Genus: Nucleosphareium Cann & Page, 1979