Assessment Notes

Justification

Pluteus fenzlii is a very rare fungus known only from several countries in Europe and Asia. It inhabits wood of broadleaved tree species. The most frequent substrate in Europe is Quercus. Basidiomata grow on fallen trunks with different diameters and branches separated from old living trees and lying on the soil. Pluteus fenzlii can be considered a species of ancient broadleaved forests.

The species is endangered by intensive forest management when no woody debris (nor branches) is left in a forest. Due to lack of awareness of this species in the past, it is not included in any national red list or list of protected species worldwide despite its rareness. Approximately 50 localities are currently known worldwide and the total number of localities can be estimated to be 500. The species has small subpopulations in Europe and also in Siberia, (no more than 1,000 mature individuals in each); in total, the number of mature individuals can be estimated to be between 5,000-10,000, with a continuing decline of its habitat quality and extension, the species is assessed as Vulnerable C2a(i).

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Taxonomic notes

There is a very similar species in North America, Pluteus mammillatus (Longyear) Minnis, Sundb. & Methven (Minnis et al. 2006), which differs from P. fenzlii only by white to greyish-red lamellar edge (yellow in P. fenzlii).

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Geographic range

Pluteus fenzlii is a Eurasian species with its main distribution in Central Europe. Currently, Slovakia (9 localities) and Hungary (5 localities) are the countries with the highest number of localities of P. fenzlii in Europe. New records or new data are recently presented or indicated from Siberia in Russia (Malysheva et al. 2016, Red Data Book of Nobosibirsk Oblast 2018, Holec et al. 2018).

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Population and Trends

Pluteus fenzlii is a rare species, ca 50 localities are currently known worldwide and total number of localities can be estimated to be 500. It occurs in Slovakia (9 localities), Hungary (5 localities), France (4 localities), Poland (1 locality) and Russia (11 regions, not less than 25 localities). In countries like Slovenia, Serbia and Croatia the species was not found for decades (Holec et al. 2018). The species has small subpopulations in Europe and also in Siberia. The number of mature individuals can be estimated to be between 5,000-10,000.

The species seems to be limited by lack of adequate substrate, like coarse woody debris of oak. In Europe oak decline (Gentilesca et al. 2017) is a potential threat. The occurrence of P. fenzlii might be also shifted by the global warming. An indication of this is that there are no recent records of the species in Balkan countries (Serbia – country of type locality, Croatia, Slovenia) but the species has been found in regions located more north (Hungary, Slovakia, Poland, continental Russia) (Holec et al. 2018).

Population Trend: decreasing

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Habitat and Ecology

Pluteus fenzlii is a wood-inhabiting fungus growing on wood of deciduous tree species in more or less natural broadleaved or mixed, sometimes more open, forest types. Based on data from Poland, Slovakia and Hungary, the substrates in this part of Europe are Quercus, Fagus sylvatica as well as Acer, Tilia, Carpinus, and Populus (Holec et al. 2018). Basidiomata grow on fallen trunks (10-55 cm in diameter) as well as branches (diameter 20 cm) separated from old living trees and lying on soil, either from decorticated wood or cracks in the bark, often at sites covered by mosses. In Russia, the species was recorded on wood of deciduous trees, particularly on Tilia, Acer and Betula (Malysheva et al. 2007, 2016).

In Asian Russia, P. fenzlii was additionally recorded in light coniferous herb forests (sub-taiga), forest-steppe, in parts with dominating Betula (Malysheva et al. 2016). 

In Europe P. fenzlii occurs in colline to montane altitudinal zones (230–425 m asl in Slovakia and France, with one exception at 740 m in France) mostly adjacent to higher mountain ranges (Pyrenees, the Carpathians, Caucasus). Exceptions are the hilly country of the Zhigulevsky State Nature Reserve in Middle Volga region (no mountain range in the vicinity) and the Białowieza National Park (lowland forest on glacial deposits, about 150 m asl). In Siberia it occurs in the planar zone.

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Threats

The species seems to be limited by lack of adequate substrate, like coarse woody debris of oak. In Europe oak decline (Gentilesca et al. 2017) is a potential threat. The species can suffer from intensive forest management practices when only a little amount or no woody debris is left in a forest (Holec et al. 2018). Most localities of P. fenzlii are in hilly landscapes (Holec et al. 2018). The decline of the old-growth oak forests in the evaluation period (50 years) is estimated to be about 30% (Hansen and Delatour 1999, Denman et al. 2014). It is expected that a similar decline of habitat and population is occurring in Russia (Teplyakov 2011).

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Conservation Actions

The key conservation action required is to protect localities with occurrence of the species. In areas with occurrence of the species which are not strictly protected, or if they can not be protected and forest management practices will continue, it is crucial to avoid clearing broadleaved forests, especially after a cutting. The most effective action in managed forests is to leave woody debris of broadleaf trees, at least branches in forests after management.

Further studies are necessary to evaluate the taxonomic status of a close Australian species following the evaluation of microcharacters variability and its possible relation to this species. Research is also needed to determine how much of decaying wood is enough for surviving of the species population at localities which are influenced by extensive forest management.

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Use and Trade

No use of fruitbodies of the fungus is known.

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Source and Citation

Brandrud, T.-E., Krisai-Greilhuber, I. & Kunca, V. 2019. Pluteus fenzlii. The IUCN Red List of Threatened Species 2019: e.T147440380A148036540. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T147440380A148036540.en .Accessed on 3 February 2025

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• Country occurrence