Monotypic eukaryote classes

Cyanidiophyceae is a class of unicellular red algae within subdivision Cyanidiophytina, and contain a single plastid, one to three mitochondria, a nucleus, a vacuole, and floridean starch. Pyrenoids are absent. Most are extremophiles inhabiting acid hot springs with a pH between 0,2 and 4 and temperatures up to 56 °C. They originated in extreme environments with high temperatures and low pH, which allowed them to occupy ecological niches without any competition.

Filasterea is a basal Filozoan clade of single-celled ameboid eukaryotes that includes Ministeria and Capsaspora. It is a sister clade to the Choanozoa in which the choanoflagellates and animals appeared, originally proposed by Shalchian-Tabrizi et al. in 2008, based on a phylogenomic analysis with 78 genes. Filasterea was found to be the sister-group to the clade composed of Metazoa and Choanoflagellata within the Opisthokonta, a finding that has been further corroborated with additional, more taxon-rich, phylogenetic analyses.

REDIRECT Diplonemidae

Tsukubamonas is a unicellular heterotrophic, biflagellated excavate of the Discoba clade (along with jakobids, euglenozoans and percolozoans) with only one species known, Tsukubamonas globosa. It inhabits fresh-water, feeds on bacteria, and can exist as a vegetative cell or cyst. The cells are characterised with a spherical or semi-spherical shape, are highly vacuolated with thin subsurface vesicles and the absence of a contractile vacuole, tubular cristae in its mitochondria, and two flagella of an apparatus with five main structures (four basal bodies, three major microtubule roots, four maj