# Anisomeridium

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***Anisomeridium*** is a [genus](/source/Genus) of [lichen](/source/Lichen)-forming [fungi](/source/Fungi) in the family [Monoblastiaceae](/source/Monoblastiaceae).[1] These lichens form thin, nearly invisible [crusts](/source/Crustose_lichen) that grow mostly embedded within the bark of trees or other surfaces. They are distinguished by their tiny flask-shaped fruiting bodies and distinctive [spores](/source/Spore) that have internal [cross-walls](/source/Septum) positioned closer to one end than the other.

## Taxonomy

The [type species](/source/Type_species) was originally named *Arthopyrenia xylogena* by the Swiss lichenologist [Johannes Müller Argoviensis](/source/Johannes_M%C3%BCller_Argoviensis) in 1883;[2] in 1928, [Maurice Choisy](/source/Maurice_Choisy) defined the genus *Anisomeridium*, designating *A. xylogena* as the type.[3]

## Description

*Anisomeridium* forms an inconspicuous crust that lies almost completely within its [substrate](/source/Substrate_(biology))—usually the bark of broad-leaved trees, but sometimes decaying wood, mosses, or shaded rock. Because the [thallus](/source/Thallus) is immersed it appears only as a faint pale-grey film or scatter of whitish patches, and it lacks a separate protective ; microscopic inspection shows a loose weft of fungal threads housing orange-tinged filaments of the green alga *[Trentepohlia](/source/Trentepohlia_(alga))*, which supplies [photosynthetic](/source/Photosynthesis) energy.[4]

[Sexual reproduction](/source/Sexual_reproduction) takes place in tiny flask-shaped fruit bodies ([perithecia](/source/Perithecia)) that are half-buried to almost fully exposed. Individual perithecia are hemispherical to nearly spherical and can merge into small compound clusters. Their wall is thicker in the upper half and commonly bears a well-defined cap (the ). A quick field test with [potassium hydroxide](/source/Potassium_hydroxide) solution turns this wall a greenish tint, helping to separate *Anisomeridium* from similar genera. Internally, the cavity is filled with a clear gel threaded by slim, long-celled that branch sparingly and fuse together, while the short hairs () found in many flask lichens are absent. Each spore sac ([ascus](/source/Ascus)) is cylindrical to club-shaped, splits lengthwise when mature (), and possesses a small lens-like ocular chamber at the tip. Eight colourless [ascospores](/source/Ascospore) are arranged in one or two rows; they are egg- to spindle-shaped, carry one to three cross-walls, and typically develop their first [septum](/source/Septum) nearer the basal end of the spore.[4]

Asexual [propagules](/source/Propagule) are just as common. Immersed or slightly protruding [pycnidia](/source/Pycnidia) produce two sizes of [conidia](/source/Conidia) in separate structures: larger macroconidia that are [ellipsoid](/source/Ellipsoid) rods and smaller microconidia that are almost spherical. Both types are simple (non-septate) and may be expelled *en masse* as a slimy white tendril. No secondary [lichen substances](/source/Lichen_substance) have been detected in European representatives of the genus, so identification relies on the combination of an almost invisible thallus, greenish K-reaction of the perithecial wall, and thin-walled, multi-septate spores with a distinctive low-end [septum](/source/Septum).[4]

## Species

As of June 2025, [Species Fungorum](/source/Species_Fungorum) accepts 35 species of *Anisomeridium*:[5]

- *[Anisomeridium americanum](/source/Anisomeridium_americanum)* (A.Massal.) R.C.Harris (1995)
- *[Anisomeridium anisolobum](/source/Anisomeridium_anisolobum)* (Müll.Arg.) Aptroot (1995)
- *[Anisomeridium australiense](/source/Anisomeridium_australiense)* (P.M.McCarthy) R.C.Harris (1995)
- *[Anisomeridium austroaustraliense](/source/Anisomeridium_austroaustraliense)* P.M.McCarthy & Kantvilas (2016)[6] – Australia
- *[Anisomeridium biforme](/source/Anisomeridium_biforme)* (Borrer) R.C.Harris (1978)
- *[Anisomeridium calcicola](/source/Anisomeridium_calcicola)* Upreti & Nayaka (2006)[7] – India
- *[Anisomeridium carinthiacum](/source/Anisomeridium_carinthiacum)* (J.Steiner) R.C.Harris (1987)
- *[Anisomeridium concameratum](/source/Anisomeridium_concameratum)* (Stirt.) Aptroot (2006)
- *[Anisomeridium consobrinum](/source/Anisomeridium_consobrinum)* (Nyl.) Aptroot (1995)
- *[Anisomeridium disjunctum](/source/Anisomeridium_disjunctum)* P.M.McCarthy & Kantvilas (2018)[8] – Australia
- *[Anisomeridium excellens](/source/Anisomeridium_excellens)* (Nyl. ex Müll.Arg.) R.C.Harris (1995)
- *[Anisomeridium foliicola](/source/Anisomeridium_foliicola)* R.Sant. & Tibell (1988)[9] – Australia
- *[Anisomeridium globosum](/source/Anisomeridium_globosum)* Aptroot, D.S.Andrade & M.Cáceres (2014)[10]
- *[Anisomeridium grumatum](/source/Anisomeridium_grumatum)* (Cooke ex Sacc.) Aptroot (1998)
- *[Anisomeridium guttuliferum](/source/Anisomeridium_guttuliferum)* Lücking (2008)
- *[Anisomeridium lateriticum](/source/Anisomeridium_lateriticum)* Aptroot & M.Cáceres (2013)[11]
- *[Anisomeridium macaronesicum](/source/Anisomeridium_macaronesicum)* van den Boom (2015)[12]
- *[Anisomeridium macropycnidiatum](/source/Anisomeridium_macropycnidiatum)* van den Boom (2015)[12]
- *[Anisomeridium platypodum](/source/Anisomeridium_platypodum)* G.Thor, Lücking & Tat.Matsumoto (2000)[13]
- *[Anisomeridium polypori](/source/Anisomeridium_polypori)* (Ellis & Everh.) M.E.Barr (1996)
- *[Anisomeridium prolongatum](/source/Anisomeridium_prolongatum)* Lücking (2008)
- *[Anisomeridium ranunculosporum](/source/Anisomeridium_ranunculosporum)* (Coppins & P.James) Coppins (2002)
- *[Anisomeridium robustum](/source/Anisomeridium_robustum)* Orange, Coppins & Aptroot (2008)[14] – Europe
- *[Anisomeridium subnectendum](/source/Anisomeridium_subnectendum)* (Nyl.) R.C.Harris (1995)
- *[Anisomeridium subnexum](/source/Anisomeridium_subnexum)* (Nyl.) R.C.Harris (1995)
- *[Anisomeridium subprostans](/source/Anisomeridium_subprostans)* (Nyl.) R.C.Harris (1980)
- *[Anisomeridium terminatum](/source/Anisomeridium_terminatum)* (Nyl.) R.C.Harris (1995)
- *[Anisomeridium tetrasporum](/source/Anisomeridium_tetrasporum)* Aptroot & Sipman (2001)[15] – Hong Kong
- *[Anisomeridium trichiale](/source/Anisomeridium_trichiale)* Aptroot & Etayo (2017)[16] – Panama
- *[Anisomeridium triseptatum](/source/Anisomeridium_triseptatum)* Aptroot & M.Cáceres (2013)[11]
- *[Anisomeridium viridescens](/source/Anisomeridium_viridescens)* (Coppins) R.C.Harris (1995)
- *[Anisomeridium yoshimurae](/source/Anisomeridium_yoshimurae)* H.Harada (2019)[17] – Japan

## References

1. Wijayawardene, Nalin; Hyde, Kevin; Al-Ani, Laith Khalil Tawfeeq; Somayeh, Dolatabadi; Stadler, Marc; Haelewaters, Danny et al. (2020). "Outline of Fungi and fungus-like taxa". *Mycosphere*. **11**: 1060–1456. [doi:10.5943/mycosphere/11/1/8](https://doi.org/10.5943/mycosphere/11/1/8). [hdl:10481/61998](https://hdl.handle.net/10481/61998)

1. Müller, J. (1883). ["Lichenologische Beiträge XVIII"](https://www.biodiversitylibrary.org/page/67631) (in Latin). *Flora*. **66** (18): 286–290.

1. Choisy, Maurice (1928). *Icones Lichenum Universalis*

1. Cannon, P.; Coppins, B.; Aptroot, A.; Sanderson, A.; Simkin, J. (2023). [*Perithecial genera I, including*Acrocordia*,*Alloarthopyrenia*,*Anisomeridium*,*Antennulariella*,*Arthopyrenia*,*Celothelium*,*Cyrtidula*,*Dichoporis*,*Eopyrenula*,*Julella*,*Leptorhaphis*,*Leptosillia*,*Lithothelium*,*Mycomicrothelia*,*Mycoporum*,*Naetrocymbe*,*Pyrenula*,*Rhaphidicyrtis*,*Sarcopyrenia*,*Swinscowia*and*Tomasellia'](https://britishlichensociety.org.uk/sites/default/files/Perithecial%20genera%20I.pdf)**. Vol. 37. Revisions of British and Irish Lichens. p. 12.**

1. [Species Fungorum](/source/Species_Fungorum). ["*Anisomeridium*"](https://www.catalogueoflife.org/data/taxon/62BFJ). *[Catalog of Life](/source/Catalog_of_Life)*. Retrieved 16 June 2025.

1. McCarthy, P.M. & Kantvilas, G. (2016). ["A new species of *Anisomeridium* (Monoblastiaceae) from Kangaroo Island, South Australia"](https://www.anbg.gov.au/abrs/lichenlist/AL79.pdf). *Australasian Lichenology*. **79**: 16–19.

1. Upreti, D.K. & Nayaka, S. (2006). "*Anisomeridium calcicolum* sp. nov. and further new records of pyrenocarpous lichens from India". *The Lichenologist*. **38** (3): 231–233. [Bibcode:2006ThLic..38..231U](https://ui.adsabs.harvard.edu/abs/2006ThLic..38..231U). [doi:10.1017/S0024282906005457](https://doi.org/10.1017/S0024282906005457)

1. McCarthy, P.M. & Kantvilas, G. (2018). ["*Anisomeridium disjunctum* (Monoblastiaceae), a new lichen species from Tasmania, with a key to the genus in Australia"](https://www.anbg.gov.au/abrs/lichenlist/AL83.pdf). *Australasian Lichenology*. **83**: 54–60.

1. Santesson, R. & Tibell, L. (1988). "Foliicolous lichens from Australia". *Austrobaileya*. **2** (5): 529–545. [doi:10.5962/p.365736](https://doi.org/10.5962/p.365736)

1. Aptroot, Andre; Andrade, Dannyelly Santos; MendonçA, CléVerton; Lima, Edvaneide Leandro De; CáCeres, Marcela Eugenia da Silva (2015). ["Ten new species of corticolous pyrenocarpous lichens from NE Brazil"](https://www.researchgate.net/publication/279318648). *Phytotaxa*. **197** (3): 197–206. [Bibcode:2015Phytx.197..197A](https://ui.adsabs.harvard.edu/abs/2015Phytx.197..197A). [doi:10.11646/phytotaxa.197.3.3](https://doi.org/10.11646/phytotaxa.197.3.3)

1. Aptroot, André & Cáceres, Marcela Eugenia da Silva (2013). "Pyrenocarpous lichens (except Trypetheliaceae) in Rondônia". *The Lichenologist*. **45** (6): 763–785. [Bibcode:2013ThLic..45..763A](https://ui.adsabs.harvard.edu/abs/2013ThLic..45..763A). [doi:10.1017/S0024282913000534](https://doi.org/10.1017/S0024282913000534)

1. Boom, P.P.G. van den (2015). "Notes on the genus *Anisomeridium* (lichenized Ascomycotina) from Madeira and the Azores (Macaronesia)". *Phytotaxa*. **205** (1): 65–70. [Bibcode:2015Phytx.205...65B](https://ui.adsabs.harvard.edu/abs/2015Phytx.205...65B). [doi:10.11646/phytotaxa.205.1.6](https://doi.org/10.11646/phytotaxa.205.1.6)

1. Thor, G.; Lücking, R.; Matsumoto, T. (2000). "The foliicolous lichen flora of Japan". *Symbolae Botanicae Upsalienses*. **32** (3): 24.

1. Coppins, Brian J. & Aptroot, André (2008). "New species and combinations in the lichens of the British Isles". *The Lichenologist*. **40** (5): 363–374. [Bibcode:2008ThLic..40..363C](https://ui.adsabs.harvard.edu/abs/2008ThLic..40..363C). [doi:10.1017/S0024282908008165](https://doi.org/10.1017/S0024282908008165)

1. Aptroot, A. & Sipman, H.J.M. (2001). ["New Hong Kong lichens, ascomycetes and lichenicolous fungi"](https://www.researchgate.net/publication/287590181). *Journal of the Hattori Botanical Laboratory*. **91**: 317–343.

1. Etayo, Javier & Aptroot, André (2017). "New and interesting lichens from Panama". *The Bryologist*. **120** (4): 501–510. [doi:10.1639/0007-2745-120.4.501](https://doi.org/10.1639/0007-2745-120.4.501)

1. Harada, H. (2019). "Taxonomic notes on pyrenocarpous lichens in Japan (11). *Anisomeridium yoshimurae* sp. nov. (Monoblastiaceae)". *Lichenology*. **18** (1): 9–13.

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