# Pyrenula cruenta

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***Pyrenula cruenta*** is a species of [corticolous](/source/Corticolous_lichen) (bark-dwelling) [crustose lichen](/source/Crustose_lichen) in the family [Pyrenulaceae](/source/Pyrenulaceae).[1] It has a [pantropical](/source/Pantropical) distribution.

## Taxonomy

The species was introduced by [Camille Montagne](/source/Camille_Montagne) in 1837 as *Trypethelium cruentum*. Montagne recorded the species on the rough bark of trees in Guiana ([French Guiana](/source/French_Guiana)), based on material collected by [Leprieur](/source/Fran%C3%A7ois_Mathias_Ren%C3%A9_Leprieur).[2] The species was later shifted between allied [pyrenocarpous](/source/Pyrenocarp) genera—[Trevisan](/source/Vittore_Benedetto_Antonio_Trevisan_de_Saint-L%C3%A9on) placed it in *Stromatothelium* (1861) and [Müller Argoviensis](/source/Johannes_M%C3%BCller_Argoviensis) in *[Melanotheca](/source/Melanotheca)* (1885)—before [Vainio](/source/Edvard_August_Vainio) transferred it to *[Pyrenula](/source/Pyrenula)* in 1890 as *Pyrenula cruenta*, the name now in use. Names since brought into [synonymy](/source/Synonym_(taxonomy)) include *Verrucaria circumrubens* [Nyl.](/source/William_Nylander_(botanist)) (1868), later [recombined](/source/Combinatio_nova) as *Pyrenula circumrubens* by [B.de Lesdain](/source/Maurice_Bouly_de_Lesdain) (1910), and *Trypethelium rubrum* [C.Knight](/source/Charles_Knight_(doctor)) (1884), which Knight himself recombined as *Melanotheca rubra* (1889).[3]

## Description

Montagne's protologue depicts a bark-dwelling lichen with a very thin, cartilage-like [thallus](/source/Thallus) that is olive-brown or sometimes so scant as to be almost invisible. The fertile parts appear as uneven, convex "warts" that often run together in short lines; he notes their "bloody" coloration, with a black interior. Each wart houses a (the flask-shaped [fruiting body](/source/Fruiting_body) typical of pyrenocarpous lichens) that is to egg-shaped and bears a small nipple-like pore ([ostiole](/source/Ostiole)). As the tissue weathers, the dark perithecial top becomes exposed and is encircled by a narrow, paler halo. The [asci](/source/Ascus) contain two-celled (1-[septate](/source/Septum)) [ascospores](/source/Ascospore) that are [ellipsoid](/source/Ellipsoid) and somewhat swollen (); each cell includes a conspicuous round oil droplet.[2] The ascospores are 27–35 [micrometres](/source/Micrometre) long.[4]

The pigment responsible for the red colour of the thallus is [draculone](/source/Draculone), an [anthraquinone](/source/Anthraquinone) compound. It is accompanied by minor amounts of [haematommone](/source/Haematommone).[5]

## Habitat and distribution

*Pyrenula cruenta* has a [pantropical](/source/Pantropical) distribution,[4] including [Florida](/source/Florida) in the United States, where it grows on sun-exposed branches of trees on lake and marsh shores.[5]

## See also

- [List of *Pyrenula* species](/source/List_of_Pyrenula_species)

## References

1. Montagne, J.P.F.C. (1837). ["Centurie de plantes exotiques nouvelles"](https://www.biodiversitylibrary.org/page/36216751) (in French). *Annales des Sciences Naturelles. Botanique*. **8**: 345–370 [357]

1. ["GSD Species Synonymy. Current Name: *Pyrenula cruenta* (Mont.) Vain., Acta Soc. Fauna Flora fenn. 7(no. 2): 197 (1890)"](https://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=403256). [Species Fungorum](/source/Species_Fungorum). Retrieved 9 November 2025.

1. Aptroot, André (2012). "A world key to the species of *Anthracothecium* and *Pyrenula*". *The Lichenologist*. **44** (1): 5–53 [24]. [doi:10.1017/S0024282911000624](https://doi.org/10.1017/S0024282911000624)

1. Mathey, Annick; Spiteller, Peter; Steglich, Wolfgang (2002). "Draculone, a new anthraquinone pigment from the tropical lichen *Melanotheca cruenta*". *Zeitschrift für Naturforschung C*. **57** (7–8): 565–567. [doi:10.1515/znc-2002-7-801](https://doi.org/10.1515/znc-2002-7-801). [PMID 12240975](https://pubmed.ncbi.nlm.nih.gov/12240975)

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