# Requienella

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Requienella
> Markdown URL: https://mediated.wiki/source/Requienella.md
> Source: https://en.wikipedia.org/wiki/Requienella
> Source revision: 1344904326
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

***Requienella*** is a small [genus](/source/Genus) of bark-dwelling [ascomycete](/source/Ascomycete) fungi in the family [Requienellaceae](/source/Requienellaceae). It was erected by [Jean-Henri Fabre](/source/Jean-Henri_Fabre) in 1883 for species with black, partly exposed [fruiting bodies](/source/Fruiting_bodies) and large, dark, many-[septate](/source/Septum) spores. The genus was long difficult to classify, and was discussed in both mycological and lichenological literature, but modern [DNA studies](/source/Molecular_phylogenetics) place it in the order *[Xylariales](/source/Xylariales)*. Most modern authors treat *Requienella* as non-[lichenised](/source/Lichen), and its species are best known from the bark of old living trees.

## Taxonomy

[Jean-Henri Fabre](/source/Jean-Henri_Fabre) introduced *Requienella* in *[Annales des Sciences Naturelles](/source/Annales_des_Sciences_Naturelles)* and dedicated the name to the botanist [Esprit Requien](/source/Esprit_Requien) of [Avignon](/source/Avignon). His original concept included four species.[1] Later revision showed that only one of them belonged in the modern sense of the genus, and Jean Boise reinstated *Requienella* in 1986 with *R. seminuda* as its [type species](/source/Type_species).[2]

Because the genus has fissitunicate-looking asci (spore-producing cells with a double-walled opening mechanism) and brown, distoseptate spores (spores with internal dividing walls), it was historically moved between several different groups of ascomycetes, including the [Dothideomycetes](/source/Dothideomycetes) and the [Pyrenulales](/source/Pyrenulales). It was also discussed in lichenological work on pyrenocarpous (flask-fruited) fungi, reflecting how uncertain the boundary between lichenised and non-lichenised taxa once seemed in this part of the fungal tree.[3][2]

A [molecular](/source/Molecular_phylogenetics) study by Jaklitsch, Gardiennet and Voglmayr in 2016 showed that *Requienella* and the related genus *[Acrocordiella](/source/Acrocordiella)* belong in *[Requienellaceae](/source/Requienellaceae)* within the *[Xylariales](/source/Xylariales)*, not with the dothideomycetes where the genus had often been placed.[4] Subsequent work on related members of *Requienellaceae* showed that the broader limits of the family were still being refined in the early 2020s, although *Requienella* remained its [type genus](/source/Type_genus) throughout.[5]

Recent authors have mainly discussed four species supported by DNA data: *R. seminuda* on [olive](/source/Olive), *R. fraxini* on [ash](/source/Ash), *R. shangrilana* from China, and *R. populi* on [aspen](/source/Aspen) in Norway.[4][6] Earlier literature also retained *R. lichenopsis* from *[Prunus](/source/Prunus)*, but it has not been included in recent molecular treatments.[2] A further species, *R. shangrilana*, was described from [Shangri-La](/source/Shangri-La,_Yunnan) in [Yunnan](/source/Yunnan), China, where it was collected as a [saprobe](/source/Saprophyte) on dead twigs of an unidentified host.[7]

## Description

*Requienella* species form small to medium-sized black [fruiting bodies](/source/Fruiting_bodies) embedded in bark. In the best-known European species these structures begin beneath the bark and later erupt through it as shiny black papillae or short cones, often with a whitish ring or patch around them that makes them conspicuous in the field.[1][4][6]

Inside the fruiting body are elongated spore-bearing sacs, or [asci](/source/Ascus), usually containing eight [ascospores](/source/Ascospore). The spores are initially colourless, then become yellow-brown to brown at maturity. They are divided by several internal partitions and have large lens-shaped chambers, giving them a segmented appearance under the microscope.[2][4]

Species are separated mainly by details of spore size and septation (the number of internal dividing walls), together with [host](/source/Host_(biology)) association. *R. fraxini* usually has mainly 3-septate spores (spores with three cross-walls), *R. seminuda* typically has five septa, and *R. populi* often develops additional longitudinal septa, making the spores partly muriform (divided in a brick-like pattern). *R. shangrilana* differs in being more deeply immersed and in having unitunicate asci (spore-producing cells with a single-walled opening mechanism) in its original description, showing that the genus remains morphologically unusual and is still not fully understood.[4][6]

## Habitat and distribution

Species of *Requienella* grow on bark, especially on old living trees with rough, well-developed bark. The European species show marked host preferences: *R. fraxini* is associated with *[Fraxinus excelsior](/source/Fraxinus_excelsior)*, *R. seminuda* with *[Olea europaea](/source/Olea_europaea)*, and *R. populi* with *[Populus tremula](/source/Populus_tremula)*.[4][6]

At least the European species do not usually seem to cause obvious damage to the host, and their nutritional mode remains uncertain. Recent authors have suggested that some may belong to a poorly understood [community](/source/Community_(ecology)) of bark-inhabiting fungi that live as [commensals](/source/Commensalism) or [endophytic](/source/Endophyte) associates rather than as aggressive [pathogens](/source/Pathogen).[6]

Geographically, *R. seminuda* is known from southern and western Europe, especially the Mediterranean region; *R. fraxini* is known from humid parts of Europe and was first reported from Norway and Sweden under the name *R. seminuda* before being separated as a distinct species; *R. populi* is so far known only from the oceanic part of western Norway.[8][4][6] The Chinese species *R. shangrilana* is known from Shangri-La in [Yunnan](/source/Yunnan), where it was collected at 3,390 m elevation on dead twigs of an unidentified host.[7] Because records have often come from targeted surveys of old trees, the genus is probably under-recorded.[8][6]

## Species

- *[Requienella fraxini](/source/Requienella_fraxini)* [4]
- *[Requienella lichenopsis](/source/Requienella_lichenopsis)* [2]
- *[Requienella populi](/source/Requienella_populi)* [6]
- *[Requienella seminuda](/source/Requienella_seminuda)* [2]
- *[Requienella shangrilana](/source/Requienella_shangrilana)* [7]

Former species:

- *Requienella alaterni* , now *[Navicella pileata](/source/Navicella_pileata)*[2]
- *Requienella olearum* , now a [synonym](/source/Synonym_(taxonomy)) of *[Requienella seminuda](/source/Requienella_seminuda)*[4]
- *Requienella princeps* , now *[Decaisnella princeps](/source/Decaisnella_princeps)*[9]
- *Requienella saccardiana* , now *[Navicella pileata](/source/Navicella_pileata)*[2]

## References

1. Fabre, J.-H. (1883). "Essai sur les Sphériacées du département de Vaucluse" (in French). *Annales des Sciences Naturelles, Botanique*. **15**: 31–69. 6.

1. Boise, Jean (1986). "Requienellaceae, a new family of Loculoascomycetes". *Mycologia*. **78** (1): 37–41. [doi:10.1080/00275514.1986.12025201](https://doi.org/10.1080/00275514.1986.12025201)

1. Aptroot, André (1998). "Aspects of the integration of the taxonomy of lichenized and non-lichenized pyrenocarpous ascomycetes". *The Lichenologist*. **30** (4–5): 501–514. [doi:10.1006/lich.1998.0151](https://doi.org/10.1006/lich.1998.0151)

1. Jaklitsch, Walter M.; Gardiennet, Alain; Voglmayr, Hermann (2016). "Resolution of morphology-based taxonomic delusions: *Acrocordiella*, *Basiseptospora*, *Blogiascospora*, *Clypeosphaeria*, *Hymenopleella*, *Lepteutypa*, *Pseudapiospora*, *Requienella*, *Seiridium* and *Strickeria*". *Persoonia*. **37**: 82–105. [doi:10.3767/003158516X690475](https://doi.org/10.3767/003158516X690475). [PMC 5238940](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5238940)

1. Dissanayake, Lakmali S.; Maharachchikumbura, Sajeewa S.N.; Mortimer, Peter E.; Hyde, Kevin D.; Kang, Ji-Chuan (2021). "*Acrocordiella yunnanensis* sp. nov. (Requienellaceae, Xylariales) from Yunnan, China". *Phytotaxa*. **487** (2): 103–113. [doi:10.11646/phytotaxa.487.2.1](https://doi.org/10.11646/phytotaxa.487.2.1)

1. Andreasen, Mathias; Jordal, J.B.; Nordén, Björn (2025). "*Requienella populi* sp. nov. (Requienellaceae, Xylariales) from the bark of living aspen trees in Western Norway". *Fungal Systematics and Evolution*. **15**: 225–234. [doi:10.3114/fuse.2025.15.10](https://doi.org/10.3114/fuse.2025.15.10). [PMC 11952183](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11952183)

1. Dissanayake, Lakmali S; Samarakoon, Milan C; Maharachchikumbura, Sajeewa SN; Hyde, Kevin D; Tang, Xia; Li, Qr; Mortimer, Peter E; Faraj, Turki; Xu, Jianchu; Kang, Ji-Chuan; Wanasinghe, Dhanushka N (2024). ["Exploring the taxonomy and phylogeny of Sordariomycetes taxa emphasizing Xylariomycetidae in Southwestern China"](https://www.mycosphere.org/pdf/MYCOSPHERE_15_1_15.pdf). *Mycosphere*. **15** (1): 1675–1793. [doi:10.5943/mycosphere/15/1/15](https://doi.org/10.5943/mycosphere/15/1/15)

1. Nordén, Björn & Jordal, John Bjarne (2014). "*Requienella seminuda*, a corticolous ascomycete on *Fraxinus excelsior* new to Norway". *Agarica*. **35**: 29–34.

1. ["*Requienella princeps* Fabre, Annls Sci. Nat., Bot., sér. 6 15: 55 (1883) \[1882\]"](https://www.indexfungorum.org/names/NamesRecord.asp?RecordID=240932). [Index Fungorum](/source/Index_Fungorum). Retrieved 17 March 2026.

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