Protosteliomycetes/Protosteliales (

ICBN The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "trad ...

) or Protostelea/Protostelia/Protosteliida ( ICZN) is a grouping of slime molds from the phylum

Mycetozoa Mycetozoa is a polyphyletic grouping of slime molds. It was originally thought to be a monophyletic clade, but recently it was discovered that protostelia are a polyphyletic group within Conosa. Classification It can be divided into dictyoste ...

. The name can vary depending upon the taxon used. Other names include Protostelea, Protostelia, and Protostelida. When not implying a specific level of classification, the term protostelid or protosteloid amoeba is sometimes used. Protosteloid amoebae, also called protostelids, are amoebae that are capable of making simple fruiting bodies consisting of a cellular stalk topped by one or a few

spores In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

. All species are microscopic and are typically found on dead plant matter where they consume

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

, yeasts, and fungal spores. Since protostelids are amoebae that make spores, they are considered to be slime molds.

Classification

It includes for example the following genera: * Cavosteliaceae (family) ** '' Cavostelium'' (genus) ** '' Planoprotostelium'' (genus) * Ceratiomyxaceae (family) ** '' Ceratiomyxa'' (genus) * Protosteliaceae (family) ** '' Protostelium'' (genus)

Taxonomy and relationships

As a subclass, Protostelia has been described as paraphyletic to the protostelid clade, as Protostelia excludes the clade of myxomycetes, which are embedded in the protostelid clade. The formal

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

of protosteloid amoebae groups them all according to fruiting bodies, mostly leaving out characteristics of the amoebae. Recent studies have shown that all protosteloid amoebae studied to date are probably included in the group known as

Amoebozoa Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported c ...

or Eumycetozoa. However, protosteloid amoebae are not all closely related and some fall within groups of amoebae in which the other amoebae are nonfruiting. Therefore, it appears that the ability to make fruiting bodies may have evolved more than once.

Ecology

Protosteloid amoebae are typically found on dead plant matter, including stems and leaves of herbaceous plants, stems and leaves of

grasses Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...

of living trees, decaying wood and other types of dead plant matter. Protosteloid amoebae are found on dead plant matter that has fallen on the ground, on dead plant parts that are still hanging in the air and on dead parts of plants that are submerged in a pond. They have also been detected on the petals of living flowers and on living tree leaves. Since protosteloid amoebae eat bacteria, yeasts, and fungal spores in the laboratory, it is thought that they also do this in nature. They are thus thought to be predators in the

decomposer Decomposers are organisms that break down dead or decaying organisms; they carry out decomposition, a process possible by only certain kingdoms, such as fungi. Like herbivores and predators, decomposers are heterotrophic, meaning that they use ...

community.

Distribution

Collections of protostelids have been made from all continents, including the Antarctic peninsula. Protostelids have also been found on isolated islands like

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...

in the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

and

Ascension Island Ascension Island is an isolated volcanic island, 7°56′ south of the Equator in the South Atlantic Ocean. It is about from the coast of Africa and from the coast of South America. It is governed as part of the British Overseas Territory o ...

in the southern

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...

, indicating that protostelids have a worldwide distribution. Most studies of protostelid distribution have been done in the

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

zones so they are best known from these areas. However,

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

studies have turned up protostelids, often in great abundance.

Collection and laboratory culture

Since protosteloid amoebae are microscopic one must bring their substrates, dead plant matter, into the laboratory to find them. Dead plant matter is placed on the

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori ('' Gracilaria'') and "tengusa" ('' Gelidiaceae''). As found in nature, agar ...

surface in a petri plate and allowed to incubate for several days to a week. Then the edges of the substrates are scanned with a

compound microscope The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microsco ...

and species are identified by their fruiting body morphology and amoebal morphology. When protosteloid fruiting bodies are found they can be moved into laboratory

culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these grou ...

onto an appropriate food organism or mix of organisms. This is done by picking up fruiting bodies or spores with a sterilised needle and moving them onto agar in a fresh petri plate that has been smeared with a bacterium or yeast upon which the protosteloid amoeba species has been known to grow. If the spores

germinate Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

then the protostelid begins eating the food organism and a culture is established. File:Ceratiomyxa.fruticulosa.jpg, '' Ceratiomyxa'' sp. File:Ceratiomyxa_Yuzhno-Sakhalinsk,_Russia._3.jpg, ''Ceratiomyxa'' sp. File:ProtsteliumMycophagaAmoeba.jpg, Amoeboid phase of '' Protostelium'' sp.

References

Eumycetozoa Amoebozoa orders {{Amoebozoa-stub