Opisthokont genera

Ministeria is a genus of Filasterea. The species can be found in the North Atlantic Ocean and in British waters.

Corallochytrium limacisporum is a species of unicellular holozoan eukaryote. It is the only species in genus Corallochytrium and the class Corallochytrea. Most research concerning this genus has been done to uncover the evolution of animals and fungi, as Corallochytrium is related to these groups and possess characteristics of both, such as animal and fungal enzymatic trademarks (C-14 reductase and α-aminoadipate reductase (α-AAR) respectively).

Syssomonas is a monotypic genus of unicellular flagellated protists containing the species Syssomonas multiformis. It is a member of Pluriformea inside the lineage of Holozoa, a clade containing animals and their closest protistan relatives. It lives in freshwater habitats. It has a complex life cycle that includes unicellular amoeboid and flagellated phases, as well as multicellular aggregates, depending on the growth medium and nutritional state.

Bicellum is a genus of fossil holozoans containing the single species Bicellum brasieri. It is one billion years old and could be the oldest example of complex multicellularity in the evolutionary lineage leading to the animals, and has been described as bridging "the gap between the very first living creatures — single-celled organisms — and more complex multicellular life." It was discovered in 2021, and is posthumously named after the late Martin Brasier, a paleontologist who was a co-author of the paper that first described it.