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65-425: Myxogastria / Myxogastrea ( myxogastrids , ICZN ) or Myxomycetes ( ICN ) is a class of slime molds that contains 5  orders , 14  families , 62  genera , and 888  species . They are colloquially known as the plasmodial or acellular slime moulds. All species pass through several very different morphologic phases, such as microscopic individual cells, slimy amorphous organisms visible with

130-469: A 35 to 40 million year old find in Baltic amber of Stemonitis splendens , an extant species. The state and completeness of the fruit bodies are remarkable, enabling accurate determination. From the same period, location and material is an Arcyria sulcata , first described in 2003 by Heinrich Dörfelt and Alexander Schmidt, a species very similar to today's Arcyria denudata . Both discoveries imply that

195-417: A combination of a generic name and a specific name ; together they make a " binomen ". No other rank can have a name composed of two names. Examples: In botanical nomenclature, the equivalent for "binominal nomenclature" is "binary nomenclature" (or sometimes " binomial nomenclature "). This is the principle that the correct formal scientific name for an animal taxon , the valid name , correct to use,

260-625: A few characteristics are diagnostic for a small number of species. In the past, authors have unsuccessfully tried to describe a new taxon based on a small number of examples, but this leads to numerous duplications, sometimes even at genus level. For example, Squamuloderma nullifila is actually a species from the genus Didymium . Echinosteliida Stemonitida Physarida Liceida Trichiida Ceratiomyxida Protosporangiida Cribrariales Reticulariales Liceida Trichiida Echinosteliida Clastodermatales Meridermatales Stemonitales Physarales The following classification

325-686: A homonymy usually produces the same problems as if there were no rules: conflicts between entirely independent and unconnected groups of taxonomists working in different animal groups. Very often the Commission must be asked to take a decision. Examples: For names above the superfamily level, the principle of homonymy does not apply. Examples: Family-rank names and genus-rank names cannot be homonyms of one another, even if identical. Example: Animal, plant, and fungi nomenclature are entirely independent from each other. The most evident shortcoming of this situation (for their use in biodiversity informatics )

390-454: A myxamoeba or a myxoflagellate buds from the spore. Myxamoebae move like amoebae – that is, crawling on the substrate – and are produced in dry conditions. Myxoflagellates, which are peritrichous and can swim, develop in moist to wet environments. Myxoflagellates almost always have two flagella; one is generally shorter than the other and sometimes only vestigial. The flagella are used for locomotion and to help to move food particles closer. If

455-431: A reticular or filamentous structure – the so-called capillitium – and are found on nearly all species except Liceida and other species from the genus Echinostelium . When the open fruit bodies have dried, the spores are dispersed by wind or by small animals such as woodlice, mites or beetles, which either pick up the spores through contact with the fruit bodies or ingest and then excrete them. Dispersal by running water

520-403: A square metre and weigh up to 20 kilograms (44 lb) ( Brefeldia maxima ). Their shape is often pediculated or unstiped sporangia with non-cellular stems, but can also appear as veined or netted plasmodiocarps , pincushion-shaped aethaliae or seemingly pincushion-shaped pseudo-aethaliae. The fruit bodies almost always have a hypothallus on the edge. The abundantly produced spores are stored in

585-426: A subgenus) are the same as for the name actually published (for example a genus). It is immaterial if there is an actual taxon to which the automatically established name applies; if ever such a taxon is recognised, there is a name available for it. This is the principle that in cases of conflicts between simultaneously published divergent acts, the first subsequent author can decide which has precedence. It supplements

650-443: Is a hardened, resistant form composed of numerous "macrocysts", which enable the myxogastria to survive in adverse conditions, for example during winter or dry periods, in this phase. Mature plasmodia can produce fruit bodies under appropriate circumstances. The exact triggers for this process are unknown. According to laboratory researchers, changes in humidity, temperature or pH value as well as starvation periods were thought to be

715-399: Is able to move towards nutrients and away from dangerous substances and light. The movements originate in the grainy cytoplasm, which streams by pulsation in one direction within the cell. In this way the cell reaches a speed of up to 1000 μm per second – the speed in plant cells is 2–78 μm per second. A resting state, the so-called sclerotium , may occur in this phase. The sclerotium

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780-493: Is also retroactive or retrospective , which means that previous editions of the code, or previous other rules and conventions have no force any more today, and the nomenclatural acts published earlier must be evaluated only under the present edition of the code. In cases of disputes a case can be brought to the commission who has the right to publish a final decision. In regulating the names of animals it holds by six central principles, which were first set out (as principles) in

845-438: Is also possible, but it plays a minor role. Some Myxogastria species may produce asexually . These are continuously diploid. There is no meiosis before the germination of the spores and the production of the plasmodium proceeds without germination of two cells. Myxogastria are distributed worldwide; species were found by early researchers on all continents. However, as many parts of the world were yet not discovered or explored,

910-638: Is based on Adl et al . (2005) while the classes and further divisions on Dykstra & Keller (2000), who included the Myxogastria in Mycetozoa. The sister taxon is the subclass Dictyostelia . Together with the Protostelia they formed the taxon Eumycetozoa . Other subclasses differ from the other species mainly in the development of fruit bodies; while Protostelia create a separate fruit body from each single mononuclear cell, Dictyostelia develop cell complexes –

975-419: Is deadwood, but also the bark of living trees ( corticolous myxomycetes ), rotting plant material, soil, and animal excrements. Slime moulds may be found in numerous unusual locations. The comprehensive group of the nivicol Myxogastria populate closed snow blankets, to quickly fructificate at exposure – for example during thaws – and release their spores. Other habitats are deserts – 33 species were found in

1040-569: Is important to cite author and year. Citing the author alone is often not sufficient. Examples: In some cases, the same genus-group or species-group name was published in the same year by the same author. In these cases it is useful to cite the page where the name was established. There are cases where two homonyms were established by the same author in the same year on the same page: Homonyms occur relatively rarely in families (only if generic names are identical or very similar and adding an ending "-idae" produces identical results). Discovering such

1105-420: Is independent of other systems of nomenclature, for example botanical nomenclature . This implies that animals can have the same generic names as plants (e.g. there is a genus Abronia in both animals and plants). The rules and recommendations have one fundamental aim: to provide the maximum universality and continuity in the naming of all animals, except where taxonomic judgment dictates otherwise. The code

1170-435: Is meant to guide only the nomenclature of animals, while leaving zoologists freedom in classifying new taxa . In other words, while species concepts (and thus the definition of species) are arbitrary to some degree, the rules for names are not. The code applies only to names. A new animal name published without adherence to the code may be deemed simply "unavailable" if it fails to meet certain criteria, or fall entirely out of

1235-431: Is that the same generic name can be used simultaneously for animals and plants. For this kind of homonym the expression "hemihomonym" is sometimes used. Far more than 1000 such names are known. Examples: This is the principle that each nominal taxon in the family group, genus group, or species group has—actually or potentially—a name-bearing type fixed that provides the objective standard of reference that determines what

1300-561: Is the oldest available name that applies to it. It is the most important principle—the fundamental guiding precept that preserves zoological nomenclature stability. It was first formulated in 1842 by a committee appointed by the British Association to consider the rules of zoological nomenclature. Hugh Edwin Strickland wrote the committee's report. Examples: There are over 2 million junior synonyms recorded in zoology, primarily at

1365-469: Is the principle that the name of each taxon must be unique. Consequently, a name that is a junior homonym of another name must not be used as a valid name. It means that any one animal name, in one particular spelling, may be used only once (within its group). This is usually the first-published name; any later name with the same spelling (a homonym ) is barred from being used. The principles of priority and first reviser apply here. For family-group names

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1430-650: Is usually necessary against them. Fossil records of Myxogastria are extremely rare. Due to their short lifespan and the fragile structures of the plasmodia and the fruit body , fossilisation and similar processes are not possible. Only their spores can be mineralised. The few known examples of fossilised living states are preserved in amber . As of 2010 three fruit bodies, two spores and one plasmodium have been described. Two older taxa – Charles Eugène Bertrand 's Myxomycetes mangini and Bretonia hardingheni from 1892 – are now considered dubious and are today often disregarded. Friedrich Walter Domke described in 1952

1495-435: The principle of priority , which states that the first published name takes precedence. The principle of the first reviser deals with situations that cannot be resolved by priority. These items may be two or more different names for the same taxon, two or more names with the same spelling used for different taxa, two or more different spellings of a particular name, etc. In such cases, the first subsequent author who deals with

1560-485: The Sonora desert , for example – or living on leaves from plants in the tropics. Some species live in aquatic environments, such as those of the genera Didymium , Physarum , Perichaena , Fuligo , Comatricha and Licea , which were found living underwater as myxoflagelletes and plasmodia. All but one species, Didymium difforme , fructificated only when the water ebbed or when they left it. The relationships of

1625-543: The cytosol of the plasmodia or even live within the strands. Certain Diptera species have evolved to specialise in this way: these are mostly representatives of the Mycetophilidae , Sciaridae and Drosophilidae . The species Epicypta testata was especially frequently found, especially on Enteridium lycoperdon , Enteridium splendens , Lycogala epidendrum , and Tubifera ferruginosa . Some true fungi specialise in

1690-540: The tropics . They are mainly found in open forests, but also in extreme regions such as deserts, under snow blankets, or underwater. They also occur on the bark of trees, sometimes high in the canopy. These are known as corticolous myxomycetes. Most species are very small. Myxomycota, now considered a synonym of Myxogastria, comes from the Ancient Greek words μύξα myxa , which means "mucus", and μύκης mykes , which means "fungus". The name Myxogastria

1755-492: The 1012 taxa only a few species are common: 305 species were discovered in a single location or groupings, a further 258 species were found in a few areas between 2–20 times, and only 446 were common in several locations with over 20 discoveries. Reclassifications encounter problems because the Myxogastriae are morphologically very plastic, which is to say susceptible to environmental influences; only

1820-615: The Arctic regions, although lack of access may be a factor. Until 1983, only 5 records were made, with only individual finds since then. According to two studies of the myxomycete flora of these regions, more species were discovered in the subantarctic forests, for example 67 species in Argentinian Patagonia and Tierra del Fuego , and 22 on high ground on Macquarie Island . The majority of Myxogastria species live terrestrially in open forests. The most important microhabitat

1885-503: The Myxogastria to other creatures have not been thoroughly researched as of 2012. Their natural predators include many arthropods , including mites and springtails , and especially beetles such as the rove beetles , round fungus beetles , wrinkled bark beetles , Eucinetidae , Clambidae, Eucnemidae (false click beetles), Sphindidae , Cerylonidae , and minute brown scavenger beetles . Various Nematodes have also been observed to be their predators; they attach their posterior portion on

1950-404: The cell to undergo enormous growth. The nucleus divides multiple times, and the cell soon becomes visible to the naked eye and usually has a surface area – depending on the species – up to one square metre; however, in 1987 one artificially cultivated cell of Physarum polycephalum attained a surface area of 5.5 sq m. Myxogastria species have numerous nuclei in their trophic plasmodium phase;

2015-461: The class is not fully described. According to a 2000 inquiry, there were 1012 officially accepted taxa , including 866 on species level. Another study in 2007 stated a number of more than 1000, in which the Myxogastria comprised the biggest group of slime moulds, with over 900 species. On the basis of sequenced environmental samples it is estimated that the group has between 1200 and 1500 species – more than previously estimated. Among

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2080-517: The colonisation of the Myxogastriae: almost all of these are species of sac fungi . The most common such fungus is Verticillium rexianum – mainly species from Comatricha or Stemonitis . Gliocladium album and Sesquicillium microsporum are often found on Physaridae, while Polycephalomyces tomentosus is often found on certain species of Trichiidae. Nectriopsis violacea specialises on Fuligo septica . Bacterial associates, mainly from

2145-452: The environmental conditions change adversely in this phase, for example extreme temperature, extreme dryness or food shortage, the Myxogastria may switch to very long-lived, thin-shelled quiescent states – the so-called micro cysts . For that to happen, the myxamoebae assume a round shape and secrete a thin cell wall. In this state they can easily survive one year or longer. If living conditions improve, they become active again. If two cells of

2210-407: The exact distribution is not fully known. Europe and North America are often considered the basic habitat of the Myxogastria species. According to recent research, the majority of species are not widely distributed. The Myxogastria are most commonly found in temperate latitudes, and rarely in the polar regions, the subtropics or tropics. The physical features of the substrate and climatic conditions are

2275-454: The family Enterobacteriaceae , were discovered on plasmodia. The combination of plasmodia and bacteria can bind atmospheric nitrogen or produce enzymes which make possible the decomposition of e.g. lignin , carboxymethylcellulose , or xylan . In a few cases, the plasmodia acquired salt tolerance or tolerance of heavy metals through this association. Some myxomycetes ( Physarum ) cause disease in plants such as turfgrasses , but no control

2340-498: The fossil was not recognised. Because of their unprepossessing nature, the Myxogastriae were for a long time not well researched. Thomas Panckow first named the mould Lycogala epidendrum as " Fungus cito crescentes" (fast-growing fungus) in his 1654 book Herbarium Portatile, oder behendes Kräuter- und Gewächsbuch . In 1729, Pier Antonio Micheli thought that fungi are different from moulds, and Heinrich Friedrich Link agreed with this hypothesis in 1833. Elias Magnus Fries documented

2405-579: The fruit bodies of the Myxogastria have changed only slightly in the last 35–40 million years. However, the Protophysarum balticum from Baltic amber, first described by Dörfelt and Schmidt in 2006, is considered questionable. The fossil was inconsistent with the typical characteristics of the genus and it was not a valid publication because no Latin name was identified with it. Also, important details of its fruit bodies were not visible or contradicted

2470-425: The high humidity which prevents the necessary dehydration of the fruit bodies to permit spore dispersal and promotes infestation by moulds. Other factors are low light levels under the forest canopy which reduces phototaxis, light winds, poor soils, natural enemies and heavy rainfall which can wash away or destroy cells. Species living in soil or deadwood decrease as humidity increases. In a study from Costa Rica, 73% of

2535-412: The humidity changes, cells can switch between the two manifestations. Neither form has a cell wall. This developmental stage (and the next one) serves as a nourishment provider and is also known as the first trophic phase (nourishment phase). In this monocellular phase, the Myxogastria consume bacteria and fungus spores, and probably dissolved substances, and they reproduce through simple cell division . If

2600-519: The identification. Today it is assumed that the fossil belongs to a lichen similar to the genus Chaenotheca . The only known discovery of a preserved plasmodium was found in Dominican amber , and was then grouped into the Physarida . However, this claim is also considered doubtful as the publication was later classified as insufficient due to lack of evidence. In 2019 sporocarps belonging to Stemonitis

2665-404: The junior and senior homonyms have been in separate genera after 1899 (Art. 57.2.1, Art. 23.9). Examples: Secondary homonyms occur when taxa with the same specific name but different original genera are later classified in the same genus (Art. 57.3, 59). A secondary homonym may only be a temporary state, as it only applies so long as two species are congeneric. Under a different classification,

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2730-459: The major aspects of the species' presence. Endemism is rare. In the northern areas, the species can be found in Alaska, Iceland, northern Scandinavia, Greenland and Russia. These are not only particular, specialised species; according to an overview study, more than 150 species were found in the arctic and subarctic regions of Iceland, Greenland, northern Russia and Alaska. These distinctly exceed

2795-506: The matter and chooses and publishes the decision in the required manner is the first reviser, and is to be followed. Example: Linnaeus 1758 established Strix scandiaca and Strix noctua (Aves), for which he gave different descriptions and referred to different types, but both taxa later turned out to refer to the same species, the snowy owl . The two names are subjective synonyms. Lönnberg 1931 acted as first reviser, cited both names and selected Strix scandiaca to have precedence. This

2860-402: The myxamoeba. The production of a zygote requires two cells of different mating types ( heterothallic ). The second trophic phase begins with the development of the plasmodium . The multinucleated organism now absorbs via phagocytosis as many nutrients as possible. These are bacteria, protists , dissolved substances, moulds, higher fungi and small particles of organic material. This enables

2925-419: The naked eye, and conspicuously shaped fruit bodies . Although they are monocellular, they can reach immense widths and weights: in extreme cases they can be up to 1 metre (3 ft 3 in) across and weigh up to 20 kilograms (44 lb). The class Myxogastria is distributed worldwide, but it is more common in temperate regions where it has a higher biodiversity than in polar regions , the subtropics , or

2990-475: The name of a genus also establishes the corresponding name of a subgenus (or vice versa): genus Giraffa Linnaeus, 1758 and subgenus Giraffa ( Giraffa ) Linnaeus, 1758 . In the family-group, publication of the name of a family, subfamily, superfamily (or any other such rank) also establishes the names in all the other ranks in the family group (family Giraffidae, superfamily Giraffoidea, subfamily Giraffinae). Author citations for such names (for example

3055-463: The plasmodial stage in 1829, and 35 years later Anton de Bary observed the germination of the spores. De Bary also discovered the cyclosis in the cell for the movement, he saw them as animal-like creatures and reclassified them as Mycetozoa , which literally translates " Fungus animals ". This interpretation prevailed until the second half of the 20th century. International Code of Zoological Nomenclature Zoological nomenclature

3120-501: The province of science (e.g., the "scientific name" for the Loch Ness Monster ). The rules in the code determine which available names are valid for any taxon in the family group, genus group, and species group. It has additional (but more limited) provisions on names in higher ranks . The code recognizes no case law . Any dispute is decided first by applying the code directly, and not by reference to precedent. The code

3185-409: The relevant other ranks with the same type. In the species-group, publishing a species name (the binomen ) Giraffa camelopardalis Linnaeus, 1758 also establishes the subspecies name (the trinomen ) Giraffa camelopardalis camelopardalis Linnaeus, 1758 . The same applies to the name of a subspecies; this establishes the corresponding species name. In the genus-group, similarly, publishing

3250-492: The same genus and same species in their original combination. The difference between a junior primary homonym and a subsequent use of a name is undefined, but it is commonly accepted that if the name referred to another species or form, gave a description, and if there is in addition no evidence the author knew that the name was previously used, it is considered as a junior homonym. Example: Typically, junior primary homonyms are permanently invalid, but some are treated as valid if

3315-410: The same type meet in this phase, they cross-fertilise to a diploid zygote through the fusion of protoplasms and nuclei . The conditions which trigger this are not known. The diploid zygote becomes a multinucleated plasmodium through multiple nuclear divisions without further cell division. If the resulting cells were peritrichous, they change their shape before the fusion from the peritrichous form to

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3380-407: The small, non-veined proto-plasmodia have between 8–100 nuclei, while large, veined meshworks have between 100 and 10 million nuclei. All of these remain part of a single cell, which has a viscous, slimy consistency, and may be transparent, white, or brightly coloured in orange, yellow, or pink. The cell has chemotactic and negative phototactic capabilities in this phase, meaning that it

3445-462: The so-called pseudo-plasmodia – from separate cells, which then become fruit bodies. Clade Myxogastria (or myxomycetes) Some classifications place part of the orders above in the subclass Myxogastromycetidae . The spores of Myxogastria are haploid , mainly round and measure between 5  μm and 20 μm, rarely up to 24 μm in diameter. Their surface is generally reticular, sharp, warty or spiky and very rarely smooth. The typical colour of

3510-442: The species level. The principle of coordination is that within the family group, genus group and species group, a name established for a taxon at any rank in the group is simultaneously established with the same author and date for taxa based on the same name-bearing type at other ranks in the corresponding group. In other words, publishing a new zoological name automatically and simultaneously establishes all corresponding names in

3575-519: The spore mass becomes visible through the structure, since the spores themselves are not pigmented. In some species, especially of the genus Badhamia , the spores produce lumps. The colour, shape and diameter of spores are important characteristics for identifying species. Important factors for the germination of spores are mainly moisture and temperature. The spores usually remain germinable after several years; there were even spores preserved in herbarium specimens which germinated after 75 years. After

3640-400: The spores' development, they first receive a diploid nucleus, and the meiosis takes place in the spore. At the germination, the spore shells open either alongside special germinal pores or chinks, or rip irregularly and then release one to four haploid protoplasts . In those species which reproduce sexually, haploid cells bud from the spores. Depending on the environmental conditions, either

3705-421: The substitute name is itself not in use. Example: Double homonymy (genus and species) may or may not be homonymy in the strict sense: if the genera are homonyms but not the same genus, the same specific names can be used in both groups, because the species are subsequently placed in different genera when the generic homonymy is removed. Example: For disambiguating one genus-group name from its homonym, it

3770-504: The termination (which is rank-bound) is not taken into account. Genera are homonyms only if exactly the same — a one-letter difference is enough to distinguish them. Examples: The following are not homonyms of Argus : The following names are not homonyms of each other: Some spelling variants are explicitly defined by the Code as being homonyms. Otherwise the one-letter difference rule applies. In species, primary homonyms are those with

3835-412: The third edition of the code (1985): This is the principle that the scientific name of a species, and not of a taxon at any other rank, is a combination of two names; the use of a trinomen for the name of a subspecies and of uninominal names for taxa above the species group is in accord with this principle. This means that in the system of nomenclature for animals, the name of a species is composed of

3900-648: The total findings were in the relatively dry Tropical Moist Forest, while 18% were in the very moist Tropical Premontane Wet Forests and only 9% in Lower Premontane Rain Forest. In the Antarctic, species were found in the South Shetland Islands , South Orkney Islands , South Georgia and the Antarctic Peninsula . Species from the Antarctic or subantarctic regions are rarer than specimens in

3965-439: The tree line. In Greenland, the habitat may reach the 77th latitude line. The Myxogastria species reach their largest biodiversity and highest frequency in forests of temperate regions, which are ideal habitats because of the amount of rich organic material, suitable humidity (not too high) and long-lasting snow cover for snow-inhabiting species. Few Myxogastria species are found in the tropics and subtropics, mainly because of

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4030-444: The triggers in some species. The plasmodia abandon their nutrient intake and crawl, attracted by light – a positive phototaxis – towards a dry, light area, to get an optimal spread of the spores. Once the fructification begins, it cannot be stopped. If disturbances occur, malformed spore-bearing fruit bodies are often produced. The plasmodium or parts of the fruit bodies can be smaller than one millimetre, in extreme cases they are up to

4095-516: The two species may no longer be in the same genus, and the junior name can potentially be used again (Art. 59.1), as long as it was not replaced before 1961, in which case it is permanently invalid (Art. 59.3). This is one of the rare cases where a single zoological species can have two entirely different names at the same time, depending upon whose classification is followed. Example: Article 59.3 states that junior secondary homonyms replaced before 1961 by substitute names are permanently invalid unless

4160-430: Was described from Burmese amber , considered to be of a mid- Cretaceous age around 99 million years old. The sporocarps are indistinguishable from extant taxa, suggesting a long morphological stasis. The only known mineralised fossils are the two spore findings from 1971, one of which, Trichia favoginea , is assumed to be from the postglacial period. In palynologian researches, by absorbing Myxogastria spores,

4225-597: Was introduced in 1970 by Lindsay Shepherd Olive to describe the family Myxogastridae, which was introduced in 1899 by Thomas Huston Macbride . Swedish mycologist Elias Magnus Fries described numerous slime moulds as Myxogasteres in 1829. Species in the class Myxogastria are colloquially known as plasmodial or acellular slime moulds. Some consider the Myxogastria a separate kingdom , with an unsettled phylogeny because of conflicting molecular and developmental data. The relations among myxogastrid orders are as yet unclear. The continuous classification of new taxa reveals that

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