# Biatoropsis

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***Biatoropsis*** is a [genus](/source/Genus) of [lichenicolous](/source/Lichenicolous_fungus) ([lichen](/source/Lichen)-dwelling) [fungi](/source/Fungi) of uncertain [familial](/source/Family_(taxonomy)) placement in the order [Tremellales](/source/Tremellales).[1] It comprises 11 species that [parasitise](/source/Parasitism) various species in the [fruticose lichen](/source/Fruticose_lichen) genera *[Usnea](/source/Usnea)* and *[Protousnea](/source/Protousnea)*.

## Taxonomy

The genus was [circumscribed](/source/Circumscription_(taxonomy)) in 1935 by the Finnish lichenologist [Veli Räsänen](/source/Veli_R%C3%A4s%C3%A4nen), who assigned *[Biatoropsis usnearum](/source/Biatoropsis_usnearum)* as the [type species](/source/Type_species).[2] The genus remained [monospecific](/source/Monospecific) for several decades, until research, starting in the 1990s,[3] showed that *B. usnearum* represented a [species complex](/source/Species_complex). Since then another ten species have been added to the genus.[4][5]

## Description

*Biatoropsis* is a genus of fungi that [parasitises](/source/Parasitism) lichens (making it [lichenicolous](/source/Lichenicolous_fungus)). The fungus produces reproductive structures called [basidiomata](/source/Basidiomata) that vary in both shape and colour, with a waxy-gelatinous texture similar to jelly.[5]

At a microscopic level, the internal tissue ([context](/source/Trama_(mycology))) consists of thread-like cells called [hyphae](/source/Hypha) that lack specialised connecting structures known as [clamps](/source/Clamp_connections). The fungus penetrates its host using specialised feeding structures called [haustoria](/source/Haustoria), which have a distinctive twisted or convoluted form characteristic of the [Tremellales](/source/Tremellales) order of fungi. The reproductive surface ([hymenium](/source/Hymenium)) contains numerous immature spore-producing cells called probasidia. These initially develop in a club-shaped form and may or may not have a clamp at their base. Unlike some related fungi, *Biatoropsis* lacks specialised sterile cells called hyphidia and cystidia in its hymenium.[5]

When fully mature, the spore-producing cells ([basidia](/source/Basidia)) are club-shaped to almost cylindrical and divided by cross-walls ([septa](/source/Septum)). These cells develop extensions called epibasidia that are roughly cylindrical in shape. The spores ([basidiospores](/source/Basidiospore)) they produce are nearly spherical to elliptical in shape and have a distinctive side projection called an apiculus. When these spores [germinate](/source/Germination), they do so by producing a tube-like growth.[5]

The fungus can also reproduce asexually in several ways. It commonly produces chains of spores called catenulate [conidia](/source/Conidia). In one rare observation, crescent-shaped (lunate) conidia were documented. In one species of *Biatoropsis*, the basidia themselves can function as cells that produce asexual spores – these spores are colourless and lack internal divisions.[5]

All species in the genus parasitise species of the [fruticose lichen](/source/Fruticose_lichen) genera *[Usnea](/source/Usnea)* and *[Protousnea](/source/Protousnea)*, causing [gall](/source/Gall)-like symptoms in infected species.[5]

## Species

As of December 2024, [Species Fungorum](/source/Species_Fungorum) (in the [Catalogue of Life](/source/Catalogue_of_Life)) accepts 11 species of Biatoropsis:[6]

- *[Biatoropsis angulatae](/source/Biatoropsis_angulatae)*
- *[Biatoropsis antarcticae](/source/Biatoropsis_antarcticae)*
- *[Biatoropsis hafellneri](/source/Biatoropsis_hafellneri)*
- *[Biatoropsis hirtae](/source/Biatoropsis_hirtae)*
- *[Biatoropsis macaronesica](/source/Biatoropsis_macaronesica)*
- *[Biatoropsis millanesiana](/source/Biatoropsis_millanesiana)*
- *[Biatoropsis minuta](/source/Biatoropsis_minuta)*
- *[Biatoropsis nigrescens](/source/Biatoropsis_nigrescens)*
- *[Biatoropsis protousneae](/source/Biatoropsis_protousneae)*
- *[Biatoropsis rubicundae](/source/Biatoropsis_rubicundae)*
- *[Biatoropsis usnearum](/source/Biatoropsis_usnearum)*

## References

1. Hyde, K.D.; Noorabadi, M.T.; Thiyagaraja, V.; He, M.Q.; Johnston, P.R.; Wijesinghe, S.N. et al. (2024). ["The 2024 Outline of Fungi and fungus-like taxa"](https://www.researchgate.net/publication/385939154). *Mycosphere*. **15** (1): 5146–6239 [5418]. [doi:10.5943/mycosphere/15/1/25](https://doi.org/10.5943/mycosphere/15/1/25). [hdl:1854/LU-8660838](https://hdl.handle.net/1854/LU-8660838)

1. Rasanen, V. (1934). "Einige neue Flechtenarten und Flechtenparasiten. 4. *Biatoropsis usnearum* gen. et sp. n" (in German). *Annales Botanici Societatis Zoologicae-Botanicae Fennicae Vanamo*. **5** (9): 8–10.

1. Diederich, Paul & Christianse, M. Skytte (1994). ["*Biatoropsis usnearum* Räsänen, and Other Heterobasidiomycetes on *Usnea*"](https://www.researchgate.net/publication/232021887). *The Lichenologist*. **26** (1): 47–66. [doi:10.1006/lich.1994.1004](https://doi.org/10.1006/lich.1994.1004)

1. Millanes, A.M.; Diederich, P.; Westberg, M.; Wedin, M. (2016). ["Three new species in the *Biatoropsis usnearum* complex"](https://www.diva-portal.org/smash/get/diva2:1053185/FULLTEXT01.pdf). *Herzogia*. **29** (2): 337–354. [doi:10.13158/heia.29.2.2016.337](https://doi.org/10.13158/heia.29.2.2016.337)

1. Diederich, Paul; Millanes, Ana M.; Wedin, Mats; Lawrey, James D. (20 August 2022). [*Flora of Lichenicolous Fungi. Basidiomycota*](https://web.archive.org/web/20241120091043/http://ps.mnhn.lu/pub/FloraLichenicolousFungi1.pdf). Vol. 1. Luxembourg: National Museum of Natural History. p. 351. ISBN 978-2-919877-26-3. Archived from [the original](https://ps.mnhn.lu/pub/FloraLichenicolousFungi1.pdf) on 20 November 2024. Retrieved 24 December 2024.

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