Trichiales

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Trichiales
Hemitrichia serpula 57955.jpg
Hemitrichia serpula
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Phylum: Amoebozoa
Class: Myxogastria
Order: Trichiales
T.Macbr. [1]
Families

Arcyriaceae
Dianemataceae
Minakatellidae
Trichiaceae

Contents

Trichiales (synonymous with Trichiida) is an order of slime moulds in the phylum Amoebozoa. Trichiales is one of five orders in the group Myxomycetes (also called Myxogastria), or the true plasmodial slime molds. [2] It is also currently categorized under the superorder Lucisporidia with its sister group, Liceales. [2] The order was first described by Thomas MacBride in 1922, [1] and has retained the same name and status as a defined order in present phylogeny. [3] In the plasmodium form,[ clarification needed ] members of Trichiales lack a columella but have a well-developed capillitium for spore dispersal. The shape and details of the capillitium are used to define families within the order. Spores are brightly coloured, ranging from clear, white and yellow to pink and red-brown tones. The order currently has 4 families, 14 genera and 174 species. [2] Recent molecular research has shown that while Trichiales probably represents a true taxonomic group, its sister group Liceales is likely paraphyletic, and it has been suggested that several genera from the Liceales should be reclassified under Trichiales instead. [2]

Etymology

"Trichiales" comes from the Greek thrix or trichos, which refers to hair or hair-like structures. [4] The taxonomy of Trichiales relies heavily on its noticeable capillitium threads, which are used to sort members into their respective families. These threads are likely the source of Trichiales's word root and name.

History of knowledge

The Myxomycetes were originally placed within the kingdom Fungi by many zoologists, despite originally being placed within the group Protista by Ernst Haekel in 1868. [5] In his 1960 publication, G.W Martin described the order “Trichiales” under the Subclass “Myxogastromycetidae” within the Myxomycetes class that he placed within the Fungi kingdom (which he called “Division: Mycota”). [6] It was later determined that the Myxomycetes were much more similar in microscopic morphology and life cycle to the Ameobozoans and since then, the order has been described multiple times as a member of the Myxomycetes within the Ameobozoans. [5]

Thomas H. MacBride first described the order as “Trichiales” in his second edition of The North American Slime Moulds, published in 1922. [1] The main features he uses to categorize the order are a capillitium formed out of distinctive threads, free branching or forming a net, as well as usually having bright yellow spores. Trichiales has also been classified with its sister group Liceales in an order called the Lamprosporales by Lister and Lister in 1925, [1] but the two were separated in subsequent works. MacBride originally used the structure of the capillitium as a morphological marker to create 5 families within the order: Dianemaceae, Perichaenaceae, Arcyriaceae, Prototrichiaceae and Trichiaceae, each given a detailed description of the capillitium threads, which MacBride described as “elaters” in reference to their ability to disperse spores. MacBride's book led to several other publications regarding the morphology and taxonomy of the Myxomycetes. This included The Myxomycetes by G.W. Martin and Constantine Alexopoulos, published in 1969, which has been and still is considered one of the most useful pieces of literature for studying the Myxomycetes. [7] In this monograph, the order of Trichiales has been simplified down to only two families: [8] Dianemaceae and Trichiaceae. Again, these two families are distinguished primarily through differences in the capillitium. The members of Dianemaceae are those that exhibit capillitium threads that are attached to the base or walls of spore and never form a net, while the Trichiaceae are categorized as having capillitium threads that are free or attached to the base of the spore, often in a net formation.

The most recent treatment of the order has four families; [2] [3] however, many researchers have noted that distinguishing these families from each other, as well as the genera, is exceedingly difficult due to the fact that many species have features and morphologies found in more than one family. Molecular research into the order Trichiales itself has only occurred very recently. The first molecular sequencing research done on the Mxyomycetes was performed in 2005 by Anne-Marie Fiore-Donno et al. [9] Before this, all taxonomy was based solely on morphology and development, seen here in Trichiales and the emphasis past researchers placed on the capillitium.

The phylogeny generated by Fiore-Donna supported the close relationship between Trichiales and Liceales as well as other taxonomy predicted by morphology. In more recent research, it has been the delineation between Trichiales and Liceales that has come into discussion. Liceales is a complex order that is not likely monophyletic due to its defining feature being the absence of a capillitium. [2] [3] Further morphological studies have revealed several species within Liceales that may in fact exhibit a capillitium. Many others that have a “pseudocapillitium”, or remnant threads within the spore, which is a poorly defined term as many different kinds of pseudocapillitium have been observed. [2] As a result, suggestions of new kinds of phylogenies based on molecular findings have been proposed. Fiore-Donna proposed the formation of new clades between Trichiales and Liceales to account for the different types of pseudocapillitiums seen. Another possible suggestion has been the break down of the Liceales order into several new clades. This would include the formation of the Trichiod clade, which would contain all the members of the Trichiales order, as well as closely related members of the Liceales order, while the rest of the Liceales order would be split amongst several other newly clades based on molecular data. [10]

Description of organism

Members of Trichiales (and indeed all the orders of the Myxomycetes) follow the typical slime mold lifecycle without much deviation. The Myxomycete life cycle consists of two trophic phases: the smaller, amoebic phase where the organism has a single nucleus and may or may not also have flagellum for motility. The other phase is the macroscopic plasmodium, which arises from the fusion of multiple cells in the amoebic phase. [11] This plasmodium is essentially a single cell with thousands of nuclei, that divide at the same time. [11] The plasmodium can reach sizes up to a meter across and moves through cytoplasmic streaming. [5] Under favorable conditions, the plasmodium is capable of forming fruiting bodies and spores, which will be released and dispersed to grow into the first amoebic phase. [11] Due to the phase being macroscopic, taxonomy of the Myxomycetes has been more heavily influenced by structures and morphology in the plasmodium than the smaller amoeboid stage. [5]

The order Trichiales is considered to be one of the endosporous myxomycetes, meaning that the spores of the organism are produced within fruiting bodies enclosed by a wall. [5] The superorder Lucisporidia, known as the “brightly-spored” or “clear –spored” slime molds lacking a columella, [2] which is an extension of the spore stalk through the structure that holds the spores. It contains the sister groups Trichiales and Liceales. Liceales is characterized by a complete lack of any capillitium [2] (although some members may exhibit a pseudocapillitum [1] ) while members of Trichiales always have a capillitium. The genera of Trichiales usually have brightly coloured spore masses, with fruiting bodies that are either fixed and immobile or forming growing stalks. [3] The spores are often yellow [1] but can range anywhere from colourless or white to pink and reddish brown. [3]

The capillitium is the defining feature of the order Trichiales. It is often described as “decorated” or “ornamental” due to features like spirals, warts, and spines. The development of the capillitium in Trichiales is formed through tubular vacuoles within the plasmodium that are organized into the desired shape of the final capillitium, including potential branches and spirals. Proteins then accumulate within these vacuoles, hardening them to form the mature structure. [12]

There have been other morphological features of the capillitium threads that have been used in the past to categorize genera and species of Trichiales. The presence of lime, or calcium carbonate within the capillitium has often been used to discern separate species. [5] Historically, members of Trichiales have not had lime deposits in their capillitium; [3] however, this technique is problematic because lime deposits can be reduced in other species due to environmental conditions. [7] This could result in an incorrect identification. [5] Another method has been to use polarized light to examine minuscule differences in the capillitium threads through the rotation of light, but this method has also been disregarded by researchers. [2]

Species of interest

Several species of Trichiales are considered some of the most common slime molds that can be observed in forests during the growing season. Species of the genera Hemitrichia, Trichia and Arcyria are numerous and easy to locate in forests from spring to late fall. [12] The genus Hemitrichia which contains an extremely beautiful and well-known species called Hemitrichia serpula. It is known for its plasmodial form, which is seen as a distinct golden-yellow network of tubes. Due to its wide spread habitat, Hemitrichia serpula has been used to study the process of speciation and gene flow in the Myxomycetes. [13] Many species of slime molds can be found in lowland forests of most of the major continents, including Asia, Europe, North America and South America, demonstrating their ability to disperse spores upwards of thousands of miles. [10]

Fossil record

Fossil records of Myxomycetes are extremely rare due to the fact that their amoeboid stage do not form fossils and their fruiting bodies in the plasmodial phase are so fragile. [14] A spore of the species Arcyria sulcata within the genus Arcyria was found preserved in amber from the Baltic forests, dating back to the Eocene period (50-35 Myr). [14] This discovery represents only one of two fossils definitively confirmed to be slime molds, and due to the poor representation slime molds have in the fossil record, it represents an important insight into the evolution of the Myxomycetes. [14]

List of families and genera

It currently has 4 families: [2] [3]

  1. Acryodes
  2. Arcyria
  3. Arcyriatella
  4. Cornuvia
  5. Perichanea
  1. Calomyxa
  2. Dianema
  1. Minakatella
  1. Calonema
  2. Hemitrichia
  3. Metatrichia
  4. Oligonema
  5. Prototrichia
  6. Trichia

Related Research Articles

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Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic multicellular or multinucleate fruiting bodies which may be formed through aggregation or fusion. Slime molds were formerly classified as fungi but are no longer considered part of that kingdom. Although not forming a single monophyletic clade, they are grouped within the paraphyletic group Protista.

<span class="mw-page-title-main">Mycetozoa</span> Infraphylum of protists

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.

<span class="mw-page-title-main">Amoebozoa</span> Phylum of protozoans

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 classification schemes, Amoebozoa is usually ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Modern studies of eukaryotic phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as several other clades comprising some 300 species of unicellular eukaryotes. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda.

<i>Physarum polycephalum</i> Species of slime mold, model organism

Physarum polycephalum, an acellular slime mold or myxomycete popularly known as "the blob", is a protist with diverse cellular forms and broad geographic distribution. The “acellular” moniker derives from the plasmodial stage of the life cycle: the plasmodium is a bright yellow macroscopic multinucleate coenocyte shaped in a network of interlaced tubes. This stage of the life cycle, along with its preference for damp shady habitats, likely contributed to the original mischaracterization of the organism as a fungus. P. polycephalum is used as a model organism for research into motility, cellular differentiation, chemotaxis, cellular compatibility, and the cell cycle.

<i>Lycogala epidendrum</i> Species of slime mould

Lycogala epidendrum, commonly known as wolf's milk or groening's slime, is a cosmopolitan species of myxogastrid amoeba which is often mistaken for a fungus. The aethalia, or fruiting bodies, occur either scattered or in groups on damp rotten wood, especially on large logs, from June to November. These aethalia are small, pink to brown cushion-like blobs. They may ooze a pink "paste" if the outer wall is broken before maturity. When mature, the colour tends to become more brownish. When not fruiting, single celled individuals move about as very small, red amoeba-like organisms called plasmodia, masses of protoplasm that engulf bacteria, as well as fungal and plant spores, protozoa, and particles of non-living organic matter through phagocytosis.

<i>Fuligo septica</i> Species of slime mould

Fuligo septica is a species of slime mold, and a member of the class Myxomycetes. It is commonly known as scrambled egg slime, or flowers of tan because of its peculiar yellowish appearance. It is also known as dog vomit slime mold or Jasmine mold and is relatively common with a worldwide distribution, often being found on bark mulch in urban areas after heavy rain or excessive watering. Their spores are produced on or in aerial sporangia and are spread by wind.

<span class="mw-page-title-main">Protosteliales</span> Group of slime moulds

Protosteliomycetes/Protosteliales (ICBN) or Protostelea/Protostelia/Protosteliida (ICZN) is a grouping of slime molds from the phylum Mycetozoa. 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.

<span class="mw-page-title-main">Myxogastria</span> Group of slime molds

Myxogastria/Myxogastrea 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.

<i>Ceratiomyxa</i> Genus of slime mould

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Fonticula is a genus of cellular slime mold which forms a fruiting body in a volcano shape. As long ago as 1979 it has been known to not have a close relationship with either the Dictyosteliida or the Acrasidae, the two well-established groups of cellular slime molds. In 1979, Fonticula was made a new genus of its own due to the unique characteristics of its fruiting body, with only one species: Fonticula alba.

<i>Enteridium lycoperdon</i> Slime mold

Enteridium lycoperdon, the false puffball, is one of the more obvious species of slime mould or Myxogastria, typically seen in its reproductive phase as a white 'swelling' on standing dead trees in the spring, or on large pieces of fallen wood. Alder is a common host.

<i>Brefeldia maxima</i> Species of slime mould

Brefeldia maxima is a species of non-parasitic plasmodial slime mold, and a member of the class Myxomycetes. It is commonly known as the tapioca slime mold because of its peculiar pure white, tapioca pudding-like appearance. A common species with a worldwide distribution, particularly in North America and Europe. It is often found on bark after heavy rain or excessive watering. Their spores are produced on or in aerial sporangia and are spread by wind, however beetles of the family Latridiidae are also reported to disperse the spores. Bonner states that soil invertebrates and rain mainly disperse spores as they are sticky and unlikely to be carried by air currents.

<span class="mw-page-title-main">Hypothallus</span>

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<i>Trichia decipiens</i> Species of slime mould

Trichia decipiens is a worldwide widespread slime mould species from the order Trichiida.

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<i>Hemitrichia</i> Genus of slime moulds

Hemitrichia is a genus of slime molds, of the family Trichiidae, found within the order Trichiida. It was first described by Josef Rostafinksi in 1873 and remains a well-defined genus of the slime molds. Hemitrichia species exhibit either plasmodiocarp or sporangium fruiting bodies, both of which are well-known and recognizable slime molds seen on multiple continents. The genus includes Hemtrichia serpula, known as the pretzel slime mold, an iconic and widespread species that has been used to examine speciation in slime molds.

<i>Elaeomyxa</i> Genus of slime moulds

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References

  1. 1 2 3 4 5 6 Macbride, T.H. (1922). The North American slime-moulds (2nd ed.). p.  237.
  2. 1 2 3 4 5 6 7 8 9 10 11 Fiore-Donno, A.; Clissmann, F.; Meyer, M.; Schnittler, M.; Cavalier-Smith, T. (2013). "Two-gene phylogeny of bright-spored myxomycetes (slime moulds, superorder lucisporidia)". PLoS.
  3. 1 2 3 4 5 6 7 8 Carlos Lado; Uno Eliasson (2017). Chapter 7 - Taxonomy and Systematics: Current Knowledge and Approaches on the Taxonomic Treatment of Myxomycetes, In Myxomycetes, edited by Steven L. Stephenson and Carlos Rojas. Academic Press. pp. 205–251.
  4. ↑ Gordh, G.; Headrick, D.H. (2001). A Dictionary of Entomology. Wallingford: CABI.
  5. 1 2 3 4 5 6 7 Olive,Lindsay (1975). The Mycetozoans. New York: Academic Press.
  6. ↑ Martin, G.W. (1960). "The Systematic Position of the Myxomycetes". Vol. 52. Mycologia, JSTOR. pp. 119–129.
  7. 1 2 Stephenson, S.L. (2011). "From morphological to molecular: studies of Myxomycetes since the monograph of Martin and Alexopoulos". Vol. 50. Fungal Diversity. pp. 21–34.
  8. ↑ Martin, G.W. and Alexopoulis, C. (1969). The Myxomycetes. Iowa City: University of Iowa Press.{{cite book}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Fiore-Donno, A.M.; et al. (2005). "Higher-order phylogeny of plasmodial slime molds (Myxogastria) based on elongation factor 1-a and small subunit rRNA gene sequences". Vol. 52. J.Eukaryotic Microbiology. pp. 201–210.
  10. 1 2 Leontyev, D.V. and Schnittler, M. (2017). "Chapter 3: The Phylogeny of Myxomycetes. In Myxomycetes, edited by Steven L. Stephenson and Carlos Rojas". Academic Press. pp. 83–106.{{cite news}}: CS1 maint: multiple names: authors list (link)
  11. 1 2 3 4 5 6 Stephenson, S.L. (2008). "Myxomycete diversity and distribution from the fossil record to the present". Vol. 17. Biodiversity & Conservation. pp. 285–301.
  12. 1 2 Alexopoulos, C. (1979). Introductory Mycology . John Wiley & Sons,Inc. ISBN   9780471022145.
  13. ↑ Heherson, N.; et al. (2017). "Speciation in progress? A phylogenetic study among populations of Hemitrichia serpula(Myxomycetes)". Vol. 12. PLoS One. pp. 1–14.
  14. 1 2 3 Dorfelt, H.; et al. (2003). "The oldest fossil myxogastroid slime mold". Vol. 107. Mycological Research. pp. 123–126.
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