# Collemopsidium

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***Collemopsidium*** is a [genus](/source/Genus) of [fungi](/source/Fungi) in the family [Xanthopyreniaceae](/source/Xanthopyreniaceae).[2] Some members of this genus are [marine](/source/Marine_fungus) species, and described as "[borderline lichens](/source/Borderline_lichen)" or "algicolous" fungi.[3]

## Taxonomy

The genus was [circumscribed](/source/Circumscription_(taxonomy)) by the Finnish lichenologist [William Nylander](/source/William_Nylander_(botanist)) in 1881, with *[Collemopsidium iocarpum](/source/Collemopsidium_iocarpum)* assigned as the [type species](/source/Type_species).[4]

## Description

Species of *Collemopsidium* form what are known as "[borderline lichens](/source/Borderline_lichens)" – relatively loose symbiotic associations between [fungi](/source/Fungi) and photosynthetic partners. The fungal portion develops an extremely thin [thallus](/source/Thallus) (body) that can either grow on the surface of the or be completely embedded within it. When growing on the surface, the thallus appears orange-brown, smooth, and shiny. Some species may develop black (blackened) ridges.[5]

The [photosynthetic](/source/Photosynthesis) partner is typically *[Hyella caespitosa](/source/Hyella_caespitosa)*, a type of [cyanobacterium](/source/Cyanobacterium) that contains an orange pigment. While this cyanobacterium normally grows as filaments when living freely on [mollusk](/source/Mollusk) shells, within the lichen partnership it usually exists as single cells measuring 3–10 [micrometres](/source/Micrometre) in diameter. These cells may be evenly scattered throughout the thallus or concentrated in clumps, giving the lichen a blotchy appearance. In some specimens growing on shells or [limestone](/source/Limestone), the photosynthetic partner may be absent.[5]

The fungal reproductive structures ([ascomata](/source/Ascomata)) can occur either singly or in groups and feature a black carbonaceous protective covering (). Each reproductive structure contains spore-producing sacs ([asci](/source/Ascus)) with eight spores that are divided into two cells (one-[septate](/source/Septum)). The internal structure includes intricately branched and persistent thread-like filaments (). The species also commonly produce smaller spore-containing structures called [pycnidia](/source/Pycnidia), which externally resemble miniature versions of the main reproductive structures. No [secondary metabolite](/source/Secondary_metabolite) have been detected in these lichens.[5]

## Habitat and distribution

*Collemopsidium* species are nearly [cosmopolitan](/source/Cosmopolitan_distribution) in distribution, occurring along [tropical](/source/Tropical), [subtropical](/source/Subtropical), [temperate](/source/Temperate), and [arctic](/source/Arctic_climate) coastlines in both hemispheres. They display considerable tolerance to variations in temperature and salinity. These lichens can be found in the eulittoral ([intertidal](/source/Intertidal_zone)) and [littoral](/source/Littoral_zone) fringe zones, growing on both [siliceous](/source/Siliceous) and [calcareous](/source/Calcareous) rock as well as on the shells of various marine organisms.[6] Records show they colonise at least 61 different species of [molluscs](/source/Mollusc) and [barnacles](/source/Barnacle), mostly in the intertidal zone, though some host species like periwinkles (*[Littorina](/source/Littorina)*) can live quite high in the littoral fringe.[6]

The significantly influences their growth patterns. On siliceous rock, the thallus always grows on the surface, and the reproductive structures remain above the substrate. On calcareous rock and shells, the thallus may grow either on the surface or become embedded within the substrate, with reproductive structures that can be either surface-level or immersed. Different forms are commonly found growing side by side on the same substrate.[6] While the lichens do not appear to harm their living substrates, they can alter the nature of shell matrices, sometimes affecting shell appearance to such an extent that it causes taxonomic confusion in limpet species.[6]

[Limestone](/source/Limestone) shores typically show less distinct zonation of lichens in the eulittoral and littoral fringe zones compared to siliceous shores, and display lower species diversity. However, *Collemopsidium* species often achieve higher coverage on limestone shores due to their ability to grow within the substrate, allowing them to persist despite erosion.[5]

## Species

As of January 2025, [Species Fungorum](/source/Species_Fungorum) (in the [Catalogue of Life](/source/Catalogue_of_Life)) accept 18 species. of *Collemopsidium*:[7]

- *[Collemopsidium angermannicum](/source/Collemopsidium_angermannicum)* (G.B.F.Nilsson) A.Nordin (2002)[8]
- *[Collemopsidium arenisedum](/source/Collemopsidium_arenisedum)* (A.L.Sm.) Coppins & Aptroot (2008)[9]
- *[Collemopsidium caesium](/source/Collemopsidium_caesium)* (Nyl.) Coppins & Aptroot (2008)[9]
- *[Collemopsidium cephalodiorum](/source/Collemopsidium_cephalodiorum)* (Triebel & Grube) Grube (2005)[10]
- *[Collemopsidium chlorococcum](/source/Collemopsidium_chlorococcum)* (Aptroot & van den Boom) Coppins & Aptroot (2008)[9]
- *[Collemopsidium foveolatum](/source/Collemopsidium_foveolatum)* (A.L.Sm.) F.Mohr (2004)[6]
- *[Collemopsidium heardense](/source/Collemopsidium_heardense)* (C.W.Dodge & E.D.Rudolph) Øvstedal (2010)[11]
- *[Collemopsidium iocarpum](/source/Collemopsidium_iocarpum)* (Nyl.) Nyl. (1881)[4]
- *[Collemopsidium japonicum](/source/Collemopsidium_japonicum)* (H.Harada) H.Harada (2004)[12]
- *[Collemopsidium kostikovii](/source/Collemopsidium_kostikovii)* Khodos. & Darmostuk (2017)[3] – Ukraine
- *[Collemopsidium mauritiae](/source/Collemopsidium_mauritiae)* Diederich & Ertz (2020)[13] – [Mauritius](/source/Mauritius)
- *[Collemopsidium monense](/source/Collemopsidium_monense)* (Wheldon) Coppins & Aptroot (2008)[9]
- *[Collemopsidium montanum](/source/Collemopsidium_montanum)* (P.M.McCarthy & Kantvilas) P.M.McCarthy (2009)[14]
- *[Collemopsidium ostrearum](/source/Collemopsidium_ostrearum)* (Vain.) F.Mohr (2004)[6]
- *[Collemopsidium pyrenuloides](/source/Collemopsidium_pyrenuloides)* C.W.Dodge & E.D.Rudolph (1955)[15] – Antarctica
- *[Collemopsidium subarenisedum](/source/Collemopsidium_subarenisedum)* (G.Salisb.) Coppins & Aptroot (2008)[9]
- *[Collemopsidium sublitorale](/source/Collemopsidium_sublitorale)* (Leight.) Grube & B.D.Ryan (2002)[16]
- *[Collemopsidium tasmanicum](/source/Collemopsidium_tasmanicum)* (P.M.McCarthy & Kantvilas) P.M.McCarthy (2009)[14]

## References

1. Bachmann, E. (1919). "Der Thallus der Kalkflechten mit *Chroolepus*-, *Scytonema*- und *Xanthocapsa*-Gonidien" (in German). *Nova Acta Academiae Caesareae Leopoldino-Carolinae Germanicae Naturae Curiosorum*. **105** (1): 1–80 [65]

1. Wijayawardene, N.N.; Hyde, K.D.; Dai, D.Q.; Sánchez-García, M.; Goto, B.T.; Saxena, R.K. et al. (2022). ["Outline of Fungi and fungus-like taxa – 2021"](https://www.researchgate.net/publication/358798332). *Mycosphere*. **13** (1): 53–453. [doi:10.5943/mycosphere/13/1/2](https://doi.org/10.5943/mycosphere/13/1/2). [hdl:10481/76378](https://hdl.handle.net/10481/76378)

1. Khodosovtsev, Olexander Ye. & Darmostuk, Valeriy V. (2017). "*Collemopsidium kostikovii* sp. nov., a new algicolous fungus on terricolous cyanobacteria crust from Ukraine". *Ukrainskiy Botanichnyi Zhurnal*. **74** (5): 431–434. [doi:10.15407/ukrbotj74.05.431](https://doi.org/10.15407/ukrbotj74.05.431)

1. Nylander, W. (1881). ["Addenda nova ad Lichenographiam europaeam. Contin. XXXV"](https://www.biodiversitylibrary.org/page/66060) (in Latin). *Flora (Regensburg)*. **64**: 2–8.

1. Pérez-Ortega, Sergio; Garrido-Benavent, Isaac; Grube, Martin; Olmo, Rocío; de los Ríos, Asunción (2016). "Hidden diversity of marine borderline lichens and a new order of fungi: Collemopsidiales (Dothideomyceta)". *Fungal Diversity*. **80** (1): 285–300. [doi:10.1007/s13225-016-0361-1](https://doi.org/10.1007/s13225-016-0361-1)

1. Mohr, Fiona; Ekman, Stefan; Heegaard, Einar (2004). "Evolution and taxonomy of the marine *Collemopsidium* species (lichenized Ascomycota) in north-west Europe". *Mycological Research*. **108** (5): 515–532. [doi:10.1017/S095375620400992X](https://doi.org/10.1017/S095375620400992X)

1. Nordin, A. (2002). "*Collemopsidium angermannicum*, a widespread but rarely collected aquatic lichen". *Graphis Scripta*. **13** (2): 39–41.

1. Coppins, Brian J. & Aptroot, André (2008). "New species and combinations in The Lichens of the British Isles". *The Lichenologist*. **40** (05): 363–374. [doi:10.1017/S0024282908008165](https://doi.org/10.1017/S0024282908008165)

1. Grube, M. (2005). "*Frigidopyrenia* – a new genus for a peculiar subarctic lichen, with notes on similar taxa". *Phyton*. **45** (2): 305–318.

1. Øvstedal, D.O. & Gremmen, N.J.M. (2010). ["Additional lichen records from Subantarctica. 2. New taxa and combinations from Îles Kerguelen, Prince Edward Islands and Heard Island"](https://www.anbg.gov.au/abrs/lichenlist/AL_67.pdf). *Australasian Lichenology*. **67**: 29–33.

1. Harada, H.; Okamoto, T.; Yoshimura, I. (2004). "A Checklist of Lichens and Lichen-allies of Japan". *Lichenology*. **2** (2): 47–166 [127]

1. Diederich, Paul & Ertz, Damien (2020). "First checklist of lichens and lichenicolous fungi from Mauritius, with phylogenetic analyses and description of new taxa". *Plant and Fungal Systematics*. **65** (1): 13–75 [33]. [doi:10.35535/pfsyst-2020-0003](https://doi.org/10.35535/pfsyst-2020-0003)

1. McCarthy, P.M. (2009). ["New combinations of Australian *Collemopsidium* Nyl. (Ascomycota, Xanthopyreniaceae)"](https://www.anbg.gov.au/abrs/li). *Australasian Lichenology*. **65**: 3.

1. Dodge, C.W. & Rudolph, E.D. (1955). ["Lichenological notes on the flora of the Antarctic Continent and the subantarctic islands. I-IV"](https://www.biodiversitylibrary.org/page/26841560). *Annals of the Missouri Botanical Garden*. **42** (2): 131–149 [133]

1. Grube, -M. & Ryan, B.D. (2002). "*Collemopsidium*". *Lichen Flora of the Greater Sonoran Desert Region*. Vol. 1. Nash, T.H.; Ryan, B.D.; Gries, C.; Bungartz, F. (eds.). Lichens Unlimited. p. 163.

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