Fungalpedia – Note 2708, Xenonectriella
Xenonectriella Weese.
Citation when using this data: Meng QF et al. – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Nectriaceae, Hypocreales, Dothideomycetes, Pezizomycotina, Ascomycota, Fungi.
Xenonectriella was originally described as Nectria lutescens by Arnold (1883). Saccardo (1883) subsequently classified this species as Pleonectria lutescens based on spore characteristics. However, upon re-examining the original specimen, Weese (1919) determined that the spores were pseudo-pluriseptato-muriformia. Consequently, Xenonectriella was established as a distinct genus, and Pleonectria lutescens was transferred to Xenonectriella lutescens.
This genus is characterized by simple, subimmersed perithecia with a soft, nectriaceous context. The asci are predominantly 2-spored, although 3- to 5-spored asci may also occur. The ascospores are elliptical to oblong, initially two-celled but later developing into pseudo-multiseptate, muriform structures. They are hyaline to brown with a verrucose surface (Weese 1919).
Since its establishment, numerous species have been added to Xenonectriella through transfers and new descriptions. Rossman (1999) transferred three species from Nectriella and Pronectria, while Etayo et al. (2008–2017) introduced eight new species and transferred four more from Nectria and Pronectria. Subsequently, Berger et al. (2020) introduced two new species and transferred another from Pronectria, with additional species described by Brackel (2014, 2016) and Spribille et al. (2020).
To date, 21 species are recognized within Xenonectriella, all of which are lichenicolous. However, the phylogenetic status of Xenonectriella remains uncertain due to the absence of sequence data in GenBank. Its classification within Nectriaceae awaits confirmation pending the availability of molecular data.
Type species: Xenonectriella lutescens (Arnold) Weese.
= Nectria lutescens Arnold ex Rehm.
Other accepted species: Species Fungorum – search Xenonectriella.
Figure 1 – Xenonectriella lutescens redrawn from Weese (1919). a Section of ascoma. b Immature and mature asci. c Mature and immature ascospores.
References
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von Brackel W. 2014 – Kommentierter Katalog der flechtenbewohnenden Pilze Bayerns. Bibliotheca Lichenologica 109, 1–476.
von Brackel W. 2016 – Eine neue flechtenbewohnende Micarea-Art aus Baden-Württemberg. Carolinea 74, 5–9.
Etayo J. 2008 – Líquenes y hongos liquenícolas del LIC de Ablitas (S. Navarra, España). Cryptogamie-Mycologie 29 (1), 63–94.
Etayo J, Navarro-Rosinés P. 2008a – Una combinación y tres especies nuevas de Lichenochora (Phyllachorales, ascomicetes liquenícolas), y notas adicionales para el género. Revista Catalana de Micologia 30, 27–44.
Etayo J, Rosato VG. 2008b – Observations on lichenicolous fungi described by Spegazzini. The Lichenologist 40, 227–232.
Etayo J, Sancho LG. 2008c – Hongos liquenícolas del sur de Sudamérica, especialmente de Isla Navarino (Chile). Bibliotheca Lichenologica 98, 1–302.
Etayo J, Berger F. 2009a – Carnegieispora rimeliae, a new genus of lichenicolous fungus from the Azores. Opuscula Philolichenum 7, 17–20.
Etayo J, Diederich P. 2009b – Arthonia protoparmeliopseos, a new lichenicolous fungus on Protoparmeliopsis muralis from Spain and Luxembourg. Bulletin de la Société des naturalistes luxembourgeois 110, 93–96.
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Etayo J, Diederich P. 2011 – Rhymbocarpus aggregatus, a new species of lichenicolous fungi (Helotiales) growing on Buellia griseovirensin Spain, with a revised key to species of the genus. Bull. Soc. Nat. luxemb. 112 35–38.
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Etayo J, Flakus A, Kukwa M, Flakus P. 2013d – Lichenochora tertia (Phyllachorales): The third species of the genus growing on Xanthoria elegans. Mycotaxon -Ithaca Ny- 113, 9–13.
Etayo J, van den Boom P. 2013e – A first checklist of lichenicolous fungi from the Dominican Republic, including the description of a new species of Xenonectriella. Opuscula Philolichenum 12 (1), 142–150.
Etayo J, Flakus A, Suija A, Kukwa M. 2015 – Macroskyttea parmotrematis gen. et sp. nov. (Helotiales, Leotiomycetes, Ascomycota), a new lichenicolous fungus from Bolivia. Phytotaxa 224 (3), 247–257.
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Saccardo PA. 1883 – Sylloge Pyrenomycetum, Vol. II. Sylloge Fungorum 2, 1–813.
Spribille T, Fryday AM, Pérez-Ortega S, Svensson M et al. 2020 – Lichens and associated fungi from Glacier Bay National Park, Alaska. The Lichenologist 52 (2), 61–181.
Weese J. 1919 – Beiträge zur Kenntnis der Hypocreaceen: Mitteilung 2. Sitzungsberichte, Akademie der Wissenschaften in Wien. Mathematisch-naturwissenschaftliche Klasse. Abteilung 1 128, 693–754.
Entry by
Meng QF, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand and School of Public Health, Zunyi Medical University, Guizhou 563000, China.
Published online 16 July 2026