# Meristacrum

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Single-species genus of fungi

Meristacrum Scientific classification Kingdom: Fungi Division: Entomophthoromycota Class: Entomophthoromycetes Order: Entomophthorales Family: Meristacraceae Humber Genus: Meristacrum Drechsler 1940 emend.[1] Tucker & Humber 1981 Type species Meristacrum asterospermum Drechsler Synonyms Pseudocoelomomyces E.A. Nam & Dubitskiĭ, 1977 (inedit.) Tabanomyces Couch, R.V. Andrejeva, Laird & Nolan, 1979

***Meristacrum*** is a fungal [genus](/source/Genus) in the monotypic [family](/source/Family_(taxonomy)) **Meristacraceae**, of the order [Entomophthorales](/source/Entomophthorales). They are parasites of soil invertebrates, they typically infect [nematodes](/source/Nematodes),[2] and [tardigrades](/source/Tardigrades).[3][4]

Fungi strains such as *Meristacrum asterospermum* and *[Zygnemomyces echinulatus](https://en.wikipedia.org/w/index.php?title=Zygnemomyces_echinulatus&action=edit&redlink=1)* have been identified as potential sources of [biological control](/source/Biological_control) against parasitic nematodes.[5] Although, they have yet to be raised within laboratory or [Axenic](/source/Axenic) conditions.[4]

## History

The family Meristacraceae was specifically erected to hold the genus *Meristacrum* in 1940.[1]

The genus *Meristacrum* gets its name from the [Greek](/source/Greek_language) word *meristos* which means 'divided'.[1]

Three genera that were formerly included in [Ancylistaceae](/source/Ancylistaceae) family; *[Ballocephala](https://en.wikipedia.org/w/index.php?title=Ballocephala&action=edit&redlink=1)*, *Meristacrum*, and *[Zygnemomyces](https://en.wikipedia.org/w/index.php?title=Zygnemomyces&action=edit&redlink=1)*, were transferred to Meristacraceae by American mycologist Richard A. Humber in 1989,[6] because these fungi all produce a simple, upright [conidiophore](/source/Conidiophore) bearing several [conidia](/source/Conidia).[2]

Genera *Ballocephala* and *Zygnemomyces* were later then transferred to subdivision [Kickxellomycotina](/source/Kickxellomycotina), based on the bifurcate, plugged septa in their vegetative hyphae,[5][7] this was also confirmed by Humber (in 2012).[8]

## Life cycle

In general, the various fungal species of Meristacraceae, find a host using a germ hyphae produced by adhesive spores that were actively (ballistically) discharged and airborne.[9] They use conidial propulsion,[10] or by 'papillar eversion', which is by fluid discharge by a swollen subtending cell, or passively released from a short pedicel.[2] Conidia then adhere to the [integument](/source/Integument) (skin) of a live [nematode](/source/Nematode), then either penetrate directly by a germ tube or germinate externally and produce secondary conidia. Resting spores germinate and produce a single erect conidiophore similar to those produced by thallodic segments[11] The fungus then invades the abdomen of the host and a systemic infection develops. Once the host has died, [sporophores](/source/Sporophores) are produced, typically between the individual segments of the abdomen, where a new generation of actively discharged spores are produced. [Resting spores](/source/Resting_spores) are often formed within the host, and the primary conidia also have the ability to produce typically smaller secondary conidia.[9][12]

## Description

They have vegetative growth which is [mycelial](/source/Mycelial) at first, then forming hyphal bodies. These are usually spherical to rounded. The Sporophores (conidiophores) are simple,[2] unbranched,[13] solitary cylindrical or slightly clavate, bearing terminal conidiogenous cells. The spores (conidia) are terminal, spherical, single celled, [unitunicate](/source/Unitunicate) (single walled),[13] and forcibly by papillar eversion or passively discharged.[13][3] The secondary spores are present or absent, either similar to primary spores and are also forcibly discharged or passively discharged from strongly narrowed and elongate sporophores. The nucleus is small, (about 3-5 μm (micron, or micrometre)[2][13]) not clearly visible during [mitosis](/source/Mitosis) and [interphase](/source/Interphase), the nucleolus is prominent,[3] and central.[2] The resting spores ([zygospores](/source/Zygospores)) are formed by hyphal conjugation (conjugation of neighbouring hyphal cells or scalariform conjugations between adjacent hyphae),[2] the zygosporangium (episore) is hyaline (glass-like or transparent) or slightly pigmented and smooth or ornamented. The zygospore (endospore) is ovoid and smooth or globose to sub-globose and roughened, germinating directly to produce secondary spores or a sporophore.[3]

## Species

As accepted by [Species Fungorum](/source/Species_Fungorum);[14]

- *[Meristacrum asterospermum](https://en.wikipedia.org/w/index.php?title=Meristacrum_asterospermum&action=edit&redlink=1)* Drechsler (1940)

- *[Meristacrum milkoi](https://en.wikipedia.org/w/index.php?title=Meristacrum_milkoi&action=edit&redlink=1)* (Dudka & Koval) Humber (1981) (syn. *Tabanomyces milkoi* (Dudka & Koval) Couch, R.V. Andrejeva, Laird & Nolan (1979))

Former species; *M. pendulatum* J.S. McCulloch (1977) is now *[Zygnemomyces pendulatus](https://en.wikipedia.org/w/index.php?title=Zygnemomyces_pendulatus&action=edit&redlink=1)*, [Mucoromycota](/source/Mucoromycota)

## References

1. ^ [***a***](#cite_ref-Dreschler_1-0) [***b***](#cite_ref-Dreschler_1-1) [***c***](#cite_ref-Dreschler_1-2) C. Dreschler, 1940, "Three new hyphomycetes preying on free-living terricolous nematodes" Mycologia 32:448-470

1. ^ [***a***](#cite_ref-zygo_2-0) [***b***](#cite_ref-zygo_2-1) [***c***](#cite_ref-zygo_2-2) [***d***](#cite_ref-zygo_2-3) [***e***](#cite_ref-zygo_2-4) [***f***](#cite_ref-zygo_2-5) [***g***](#cite_ref-zygo_2-6) ["Meristacraceae | Zygomycetes"](https://www.zygomycetes.org/index.php?id=31). *www.zygomycetes.org*. Retrieved 4 January 2023.

1. ^ [***a***](#cite_ref-Cannon_3-0) [***b***](#cite_ref-Cannon_3-1) [***c***](#cite_ref-Cannon_3-2) [***d***](#cite_ref-Cannon_3-3) P. F. Cannon and P. M. Kirk (Editors) *[Fungal Families of the World (2007)](https://books.google.com/books?id=Lw1VLSH1xnAC&pg=PA210)*, p. 210, at [Google Books](/source/Google_Books)

1. ^ [***a***](#cite_ref-McLaughlin2014_4-0) [***b***](#cite_ref-McLaughlin2014_4-1) David J. McLaughlin and Joseph W. Spatafora (Editors) *[Systematics and Evolution: Part A (2014)](https://books.google.com/books?id=SuZhBAAAQBAJ&pg=PA223)*, p. 223, at [Google Books](/source/Google_Books)

1. ^ [***a***](#cite_ref-Saikawa1997_5-0) [***b***](#cite_ref-Saikawa1997_5-1) Saikawa, Masatashi; Oguchi, Masami; Castañeda Ruiz, Rafael F (1997). "Electron microscopy of two nematode-destroying fungi, *Meristacrum asterospermum* and *Zygnemomyces echinulatus* (Meristacraceae, Entomophthorales)". *Canadian Journal of Botany*. **75** (5): 762–768. [doi](/source/Doi_(identifier)):[10.1139/b97-086](https://doi.org/10.1139%2Fb97-086).

1. **[^](#cite_ref-Humber_1989_6-0)** Humber RA. ["Synopsis of a revised classification for the Entomophthorales (Zygomycotina)"](http://www.cybertruffle.org.uk/cyberliber/59575/0034/002/0441.htm). *Mycotaxon*. **34** (2): 441–60 (see p. 453).

1. **[^](#cite_ref-7)** Saikawa, Masatoshi (February 2011). "Ultrastructure of the septum in Ballocephala verrucospora (Entomophthorales, Zygomycetes)". *Canadian Journal of Botany*. **67** (8): 2484–2488. [doi](/source/Doi_(identifier)):[10.1139/b89-318](https://doi.org/10.1139%2Fb89-318).

1. **[^](#cite_ref-8)** Humber, Richard A. (December 2012). "Identification of entomopathogenic fungi". *Manual of Techniques in Invertebrate Pathology*. Cornell University. pp. 151–187.

1. ^ [***a***](#cite_ref-Batt_9-0) [***b***](#cite_ref-Batt_9-1) Carl A. Batt and Pradip Patel (Editors) *[Encyclopedia of Food Microbiology (2014)](https://books.google.com/books?id=1b1CAgAAQBAJ&pg=PA59)*, p. 59, at [Google Books](/source/Google_Books)

1. **[^](#cite_ref-10)** Drechsler, Charles (1960). ["Conidial Propulsion in *Meristacrum Asterospermum*"](https://www.biodiversitylibrary.org/part/139519). *Sydowia*. **14**: 98–103.

1. **[^](#cite_ref-Davidson_11-0)** Davidson, J. G. N.; Barron, G. L. (January 2011). "Nematophagous fungi: Meristacrum". *Canadian Journal of Botany*. **51** (1): 231–233. [doi](/source/Doi_(identifier)):[10.1139/b73-031](https://doi.org/10.1139%2Fb73-031).

1. **[^](#cite_ref-12)** Frank Matthews Dugan *[The Identification of Fungi: An Illustrated Introduction with Keys, Glossary, and Guide to Literature (2006)](https://books.google.com/books?id=3IHwAAAAMAAJ&pg=PA19)*, p. 19, at [Google Books](/source/Google_Books)

1. ^ [***a***](#cite_ref-Howard_13-0) [***b***](#cite_ref-Howard_13-1) [***c***](#cite_ref-Howard_13-2) [***d***](#cite_ref-Howard_13-3) D.H. Howard (Editor) *[Pathogenic Fungi in Humans and Animals (2002)](https://books.google.com/books?id=my7KbbJi2b4C&pg=PA130)*, p. 130, at [Google Books](/source/Google_Books)

1. **[^](#cite_ref-Fungorum_14-0)** ["Meristacrum - Search Page"](http://www.speciesfungorum.org/Names/Names.asp?strGenus=Meristacrum). *www.speciesfungorum.org*. Species Fungorum. Retrieved 4 January 2023.

Taxon identifiers Meristacraceae Wikidata: Q4290939 Wikispecies: Meristacraceae AusFungi: 60013650 CoL: CLS EoL: 6329 EPPO: 1MERSF GBIF: 8273 IndexFungorum: 82028 IRMNG: 108181 ITIS: 936669 MycoBank: 82028 NBN: NHMSYS0001489360 Open Tree of Life: 4039181 SpeciesFungorum: 82028 Meristacrum Wikidata: Q10581854 Wikispecies: Meristacrum AusFungi: 60016172 CoL: 5PBK EoL: 23127 EPPO: 1MERSG GBIF: 2559550 IndexFungorum: 20325 IRMNG: 1342902 MycoBank: 20325 Open Tree of Life: 3687118 SpeciesFungorum: 20325

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Adapted from the Wikipedia article [Meristacrum](https://en.wikipedia.org/wiki/Meristacrum) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Meristacrum?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.