The Stramenopiles, also called Heterokonts, are a clade of organisms distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, and in some they have been secondarily lost. Stramenopiles represent one of the three major clades in the SAR supergroup, along with Alveolata and Rhizaria.
The opisthokonts are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and Breviata comprise the larger clade Obazoa.
The Ichthyosporea are a small group of Opisthokonta in Eukaryota, mostly parasites of fish and other animals.
The Apusozoa are a paraphyletic phylum of flagellate eukaryotes. They are usually around 5–20 μm in size, and occur in soils and aquatic habitats, where they feed on bacteria. They are grouped together based on the presence of an organic shell or theca under the dorsal surface of the cell.
Capsaspora is a monotypic genus containing the single species Capsaspora owczarzaki. C. owczarzaki is a single-celled eukaryote that occupies a key phylogenetic position in our understanding of the origin of animal multicellularity, as one of the closest unicellular relatives to animals. It is, together with Ministeria vibrans, a member of the Filasterea clade. This amoeboid protist has been pivotal to unravel the nature of the unicellular ancestor of animals, which has been proved to be much more complex than previously thought.
Corallochytrium belongs to the class of Corallochytrea within Teretosporea and is a sister group to Ichthyosporea. Corallochytrium limacisporum is the only species of Corallochytrium known so far. It was first discovered and named in the Arabian Sea’s coral lagoons by Kaghu-Kumar in 1987. It was first thought to be a member of the fungi-like thraustochytrids, however, this was later disproven due to Corallochytriums lack of cilia and sagenogenetosome. Little research has been done on the life cycle or morphology. Most research concerning this genus has been done to uncover the evolution of animals and fungi, as Corallochytrium possess both animal and fungal enzymatic trademarks.
Holozoa is a clade of organisms that includes animals and their closest single-celled relatives, but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms, including around 300 unicellular species. It consists of various subgroups, namely Metazoa and the protists Choanoflagellata, Filasterea, Pluriformea and Ichthyosporea. Along with fungi and some other groups, Holozoa is part of the Opisthokonta, a supergroup of eukaryotes. Choanofila was previously used as the name for a group similar in composition to Holozoa, but its usage is discouraged now because it excludes animals and is therefore paraphyletic.
Amoebidiidae is a family of single-celled eukaryotes, previously thought to be zygomycete fungi belonging to the class Trichomycetes, but molecular phylogenetic analyses place the family with the opisthokont group Mesomycetozoea. The family was originally called Amoebidiaceae, and considered the sole family of the fungal order Amoebidiales that included two genera: Amoebidium and Paramoebidium. However, Amoebidiidae is now monogeneric as it was recently emended to include only Amoebidium. Species of Amoebidium are considered obligate symbionts of freshwater-dwelling arthropod hosts such as midge larvae and water fleas (Daphnia). However, because Amoebidium species attach to the exoskeleton (exterior) of the host and grow in axenic culture, at least some species may be facultative symbionts.
Perkinsids are single-celled protists that live as intracellular parasites of a variety of other organisms. They are classified as the class Perkinsea within the monotypic phylum Perkinsozoa. It is part of the eukaryotic supergroup Alveolata, along with dinoflagellates, their closest relatives, and another parasitic group known as Apicomplexa. Perkinsids are found in aquatic environments, as parasites of dinoflagellates and various animals.
Creolimax fragrantissima is a single-celled protist that occupies a key phylogenetic position to understand the origin of animals. It was isolated from the digestive tract of some marine invertebrates, mainly from the peanut worm, collected from the Northeast Pacific.
Amoebidium is a genus of unicellular, symbiotic eukaryotes in the Opisthokont group Mesomycetozoea, family Amoebidiidae. Amoebidium species attach to the exoskeleton of freshwater aquatic arthropods such as midge larvae and water fleas (Daphnia). The type species is Amoebidium parasiticum, which is also one of the only species to be cultured axenically.
Paramoebidium is a genus of unicellular, symbiotic eukaryotes that inhabit the digestive tract of immature freshwater arthropod hosts. Paramoebidium is classified in the opisthokont class Mesomycetozoea, and is the sole genus in the family Paramoebidiidae. Prior to 2005, Paramoebidium species were tentatively placed with the fungal group Trichomycetes due to their habitation of arthropod guts, host overlap between various Paramoebidium and fungal trichomycete taxa, and similar vegetative growth form.
Paramoebidiidae is a family of single-celled eukaryotes, previously thought to be zygomycete fungi belonging to the class Trichomycetes, but molecular phylogenetic analyses place the family with the opisthokont group Mesomycetozoea. The family was originally called Amoebidiaceae, and considered the sole family of the fungal order Amoebidiales that included two genera, Amoebidium and Paramoebidium. However, Paramoebidium is now the sole genus of the family Paramoebidiidae and Amoebidiidae is likewise monogeneric as it was recently emended to include only Amoebidium. Species of Paramoebidium are obligate symbionts of immature freshwater-dwelling arthropod hosts such as mayfly and stonefly nymphs and black fly larvae. Paramoebidium species attach to the digestive tract lining of their host via a secreted holdfast.
Abeoforma whisleri is a single-celled eukaryote that belongs to the Ichthyosporea clade, a group of protists closely related to animals.
Sphaeroforma arctica, is a unicellular eukaryote with a pivotal position in the tree of life. It was first isolated from the arctic marine amphipod Gammarus setosus. Like other Ichthyosporeans such as Creolimax and Abeoforma, Sphaeroforma arctica are spherical cells characterized with their capacity to grow into multi-nucleated coenocytes. However, a unique feature of S. arctica, is that no obvious budding, hyphal, amoeboid, sporal or flagellated growth stages have been observed in laboratory growth conditions.
Mantamonads are a group of free-living heterotrophic flagellates that move primarily by gliding on surfaces. They are classified as one genus Mantamonas in the monotypic family Mantamonadidae, order Mantamonadida and class Glissodiscea. Previously, they were classified in Apusozoa as sister of the Apusmonadida on the basis of rRNA analyses. However, mantamonads are currently placed in CRuMs on the basis of phylogenomic analyses that identify their closest relatives as the Diphylleida and Rigifilida.
Parvularia atlantis is a filopodiated amoeba which was isolated from a lake in Atlanta and deposited in the American Type Culture Collection (ATCC) under the name Nuclearia sp. ATCC 50694 on 1997 by TK Sawyer. It was classified under the genus Nuclearia and morphologically resembles to Nuclearia species, although it is smaller. Later it was determined that it phylogenetically belongs to a new nucleariid lineage., distantly related to Nuclearia and Fonticula genera – the other two previously described nucleriid genera.
Hyalochlorella marina, the only species in the genus Hyalochlorella and also known as Dermocystidium sp., is a marine heterotrophic eukaryote with uncertain phylogenic position.
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.
Colponemids are free-living alveolates, unicellular flagellates related to dinoflagellates, apicomplexans and ciliates. They are predators of other small eukaryotes, found in freshwater, marine and soil environments. They do not form a solid clade, but a sparse group of deep-branching alveolate lineages.
