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Flaviporus citrinellus (Niemelä & Ryvarden) Ginns

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Scientific name
Flaviporus citrinellus
Author
(Niemelä & Ryvarden) Ginns
Common names
Zitronengelbe Krustentramete
Lemon-colored Antrodiella
outkovečka citronová
Sidrunkollane antrodiell
IUCN Specialist Group
Mushroom, Bracket and Puffball
Kingdom
Fungi
Phylum
Basidiomycota
Class
Agaricomycetes
Order
Polyporales
Family
Meruliaceae
Assessment status
Published
Proposed by
Irmgard Krisai-Greilhuber
Assessors
Irmgard Krisai-Greilhuber
Editors
Susana C. Gonçalves
Contributors
Daniel Dvořák, Reda Iršėnaitė, Irja Saar
Comments etc.
Anders Dahlberg

Assessment Notes

R-L categories correct, but text here does not match final assessment. Developed and updated version published at IUCN´s Red List update, July 18th 2019.

Justification

Flaviporus citrinellus is a lemon yellow wood-inhabiting annual polypore.  It is present in Scandinavia, rare in West and Central Europe and expands to Russia. It causes white rot mainly on Picea abies preferring wet swampy localities. It also occurs on Abies alba and is reported from Fagus and Betula pubescens. Most records are from montane and supra-montane spruce forests (ca. 1000-1300 m) and submontane to montane mixed forests dominated by beech, spruce and fir. Almost all records are from fallen trunks 10–100 cm in diameter, rarely stumps. Naturalness of the localities was checked and it could be shown that F. citrinellus clearly prefers virgin, natural and near-natural spruce forest and spruce-beech-fir forest stands, i.e. old-growth forests, therefore it can be used as an indicator of this habitat. Phenologically this species seems to be almost always associated with the very abundant polypore Fomitopsis pinicola. Fruit bodies develop mainly in late autumn (October, November) and again in spring (April to June). It is generally extremely rare, but locally common and may have been overlooked because of its special phenology in colder periods and occurrence on the underside of logs and in crevices. Its existence seems to depend on high humidity, high amount of woody debris and the occurrence of Fomitopsis pinicola. In the presence of living A. citrinella fruit bodies, fruit bodies of F. pinicola were found to be always dead. This supports speculations that the relation may be parasitic on the hyphae of Fomitopsis.
Adequate moist habitats, wet climate and a high amount of dead wood within reach is an important prerequisite for the occurrence of A. citrinella. The species is a major indicator species for montane old-growth forests where it has its retreat area and should be considered by authorities and conservationists when negotiating protected sites.
Unmanaged forests are highly endangered by logging and management changes in many European countries, e.g. in Austria, only 3 % of Austrian forests are virgin forests (including very steep inaccessible ones) and Carbonate- and clay-spruce-fir-beech-forests, habitats of occurrence of Antrodiella, are endangered biotopes types (Essl & Egger 2010). As an inhabitant of natural and near-natural forest with high humidity and a high amount of coarse dead-wood the species is threatened by habitat destruction and anthropogenous habitat changing like logging, removing of dead wood and drainage. It may also be endangerd by warming due to climate change as it has its growth optimum at rather low temperatures (5-10 °C). It is red-listed in 9 European countries. Based on GBIF and databases available (see below) 230 subpopulations are known worldwide. The number of mature individuals has been estimated at 2760. The total area of occurrence was estimated as being 1840 km2.
Following criteria A, B and C it is Vulnerable: A3c: decline in AOO suspected due to decline of natural and nature-like forests, i.e. habitat loss, and quality changes, B2ab(iii), because AOO: 1840 km2, and C2ai, because of small population size. Number of mature individuals only 2760 and number of mature individuals in each subpopulation < 250.
The assessment is based on quite small population size, fragmentation, loss of habitat and a diminishing habitat quality.


Taxonomic notes

Synonymy:
Antrodiella citrinella Niemelä & Ryvarden, Karstenia 23(1): 26 (1983)


Why suggested for a Global Red List Assessment?

It is red-listed in nine European countries. It occurs only in very humid natural and near-natural forests with a very high supply of high-quality deadwood, that is coarse woody debris. As suitable habitats are often declining, it is therefore endangered with the exception of Scandinavia and rare in Europe.


Geographic range

It is known in Europe in the north in Scandinavia, rare in Western (France) and Central Europe and expands east to Russia (how far east?). Known Localities (number in brackets): Czech Republic (31), Estonia (29), Lithuania (4), Germany (7), Austria (3), Norway (66), Sweden (25), Switzerland (13), Poland (1), Russian Federation (100), Greece (1 – adventive), Finland (130), France (1), Slovakia (4), Bosnia & Herzegovina (1), Croatia (1).


Population and Trends

Based on GBIF and databases available (see below) 230 subpopulations are known worldwide. The number of mature individuals has been estimated at 2760 following these lines: (a) likely number of current localities (estimated to be ca. 460) (b) translation of the estimated total number of localities to an estimate of the total number of mature individuals in 2 steps (i calculate the number of functional individuals (ie. conspecific sporomata inhabiting an individual tree, template = 2, = 1380): estimation of total number of localities × estimation of the average number of functional individuals/locality; ii convert the number of functional individuals into mature individuals following Dahlberg & Mueller 2011, template = 2 because few aggregates sporomata on a trunk should be counted as two mature individuals; = 2760). The number of known localities is 230 and the number of yet unknown localities was estimated to be twice as high. Mature individuals are very rare. The AOO was estimated as being 1840, based on 2 x 2 m = 4 km2 for each locality, because almost all of the basidiospores of a mature fruit body are deposited within this area (Norros et al. 2012). Functional individuals of lignicolous fungi have to be calculated per trunk or log because of the mycelia (ramets) inhabiting the log, stump or root. For the AOO one has also to consider spore dispersal distance. Most spores of a mature individual are dispersed within 10s of metres, only a minor proportion is dispersed over longer distances. Due to competition with other spores and other environmental factors (e.g. wood degradation stage, succession stage), colonization ability leading to a new generation via spore germination and establishment is only possible with a high number of spores deposited. This high number is only reached within the above mentioned 60-80 m, meaning that the AOO of a single ramet and its offspring is no more than 80 m. So calculating with the suggested 2 x 2 km2 is more than sufficient for AOO. For taxa that have a cryptic life form (such as fungi) occurrences may be estimated by tallying the area of 2 x 2 km2 (= 4 km2) grid cell in which observation records are located using equation 4.1. (IUCN Guidelines 2017): AOO = no. occupied cells × area of an individual cell. As it is still very difficult to have accurate distribution data, in case of macromycetes the no. of occupied cells is equated with no. of sites known.

Population Trend: Uncertain


Habitat and Ecology

Antrodiella citrinella (Flaviporus citrinellus) is a rare wood-inhabiting annual polypore causing white rot mainly on Picea abies preferring wet swampy localities. It also occurs on Abies alba and is reported from Fagus and Betula pubescens. It occurs on slopes of hills and mountains and at bottoms of deep river or stream valleys in waterlogged spruce forests and ravine forests. Most records are from montane and supra-montane spruce forests (ca. 1000-1300 m) and submontane to montane mixed forests dominated by beech, spruce and fir. In Switzerland it fruits also in lowlands below 600 m. Picea abies is the preferred substrate, followed by Abies alba, Fagus sylvatica and basidiomata of Fomitopsis pinicola. Almost all records are from fallen trunks 10–100 cm in diameter, rarely stumps or pieces of wood (Greece). In Czech Republic the wood decay stage is 2–5, its peak in stage 3 and naturalness of the localities was checked and it could be shown that A. citrinella clearly prefers virgin, natural and near-natural forest stands, i.e. old-growth forests, therefore it can be used as an indicator of this habitat. Only one locality is in a managed stand. The occasional collection of Greece from the seashore has to be classified as adventive because its substrate was construction wood imported from Norway. Its main habitats are natural or near-natural spruce forest and spruce-beech-fir forest.
Phenologically this species seems to be almost always associated with the very abundant polypore Fomitopsis pinicola. Whereas perennial fruitbodies of F. pinicola develop over the year from spring to autumn, the annual rare red-data list species Antrodiella citrinella develops fruit bodies mainly in late autumn (October, November) and again in spring (April to June). Growth studies on agar media confirmed that A. citrinella grows faster at lower temperatures (5-10 °C), whereas F. pinicola is clearly superior in growth rate between 15 °C and 25 °C. This indicates that A. citrinella is a generally extremely rare, but locally common species that may have been overlooked because of its special phenology in colder periods. However, the yellow fruit bodies are very conspicuous and characteristic, which makes it easily identifiable, but it occurs not only directly on dead Fomitopsis fruit bodies, it also grows directly on bare decorticated wood on the underside of huge logs or in crevices or underneath the bark and is difficult to find. Its existence seems to depend on high humidity, high amount of woody debris (P. abies) and the occurrence of F. pinicola. In the presence of living A. citrinella fruit bodies, fruit bodies of F. pinicola were found to be always dead. This supports earlier speculations that the relation may be parasitic on the hyphae and/or fruit bodies of Fomitopsis.
Adequate moist habitats, wet climate and a high amount of dead wood within reach is an important prerequisite for the occurrence of A. citrinella. The species is a major indicator species for montane old-growth forests where it has its retreat area and should be considered by authorities and conservationists when negotiating protected sites.
Dvořák et al. (2017) showed the unmanaged forests are the species-richest and stand out in richness of wood-inhabiting fungi. The highest number of indicator species, predominantly wood-inhabiting fungi, was associated with unmanaged stands. In some countries, e.g. Czech Republic, Norway, records of Antrodiella are quite numerous and recent. The fruit bodies are quite hidden and difficult to find, also due to its occurrence out of the main seaso. Mycologists now are more aware of it and it might be more frequently recorded than in the past. 

Unmanaged forests are highly endangered by logging and management changes in many European countries, e.g. in Austria, only 3 % of Austrian forests are virgin forests (including very steep inaccessible ones) and Carbonate- and clay-spruce-fir-beech-forests, habitats of occurrence of Antrodiella, are endangered biotopes types (Essl & Egger 2010).
Adequate moist habitats, wet climate and a high amount of dead wood within reach is an important prerequisite for the occurrence of A. citrinella. The species is a major indicator species for montane old-growth forests where it has its retreat area and should be considered by authorities and conservationists when negotiating protected sites.

Boreal ForestTemperate Forest

Threats

As an inhabitant of natural and near-natural forest with high humidity and a high amount of coarse dead-wood the species is threatened by habitat destruction and anthropogenous habitat changing like logging, removing of dead wood and drainage. It may also be endangerd by warming due to climate change as it has its growth optimum at rather low temperatures (5-10 °C).

Unintentional effects: large scale (species being assessed is not the target) [harvest]Abstraction of ground water (agricultural use)Habitat shifting & alterationTemperature extremes

Conservation Actions

Protection of natural and near natural forest sites needed, no forest management at the protected sites except game management in a certain amount to guarantee tree growth and young tree regeneration, leaving of a high amount of high quality, that is coarse, dead wood.
Fortunately, in Czech Republic, most of the Antrodiella localities are protected as nature reserves or strictly protected zones of national parks. This is not the case in other countries, e.g. in Austria. In Sweden two of the known three sites are protected.

Site/area protectionResource & habitat protectionSite/area management

Research needed

Research on population size, population trends and distribution monitoring are needed.

Population size, distribution & trends

Use and Trade

There is no use and trade known.


Bibliography

https://www.grzyby.pl.pl/gatunki/Flaviporus_citrinellus.htm
https://www.gbif.org/
https://swissfungi.wsl.ch/de/verbreitungsdaten/verbreitungsatlas.html

Dahlberg, A., Mueller, G., 2010: Applying IUCN red-listing criteria for assessing and reporting on the conservation status of fungal species. Fungal Ecology 4: 147-162.

David, A., Tortič, M., 1986:  Contribution ä l’etude de quatre Polypores europeens peu connus. Cryptogamie Mycol., 7 (1), p. 1-13.

Dvořák, D., Vašutová, M., Hofmeister, J., Beran, M., Hošek, J., Bĕťák, J., Burel, J., Deckerová, H. 2017: Macrofungal diversity patterns in central European forests affirm the key importance of old-growth forests. Fungal Ecology 27: 145-154.

Essl, F., Egger, G., 2010: Lebensraumvielfalt in Österreich – Gefährdung und Handlungsbedarf. Zusammenschau der Roten Liste gefährdeter Biotoptypen Österreichs. – Naturwissenschaftlicher Verein für Kärnten und Umweltbundesamt GmbH.

Holec J., Běťák J., Pouska V., Dvořák D., Zíbarová L., Kout J., Adam D. (2018): Old-growth forest fungus Antrodiella citrinella – distribution and ecology in the Czech Republic. – Czech Mycol. 70(2): 127–143. http://www.czechmycology.org/_cmo/CM70203.pdf#page=1

UCN Standards and Petitions Subcommittee. 2017. Guidelines for using the IUCN Red List Categories and Criteria. Version 13. Prepared by the Standards and Petitions Subcommittee. http://nc.iucnredlist.org/redlist/content/attachment_files/RedListGuidelines.pdf

Niemelä, T., Kotiranta, H., Penttilä, R., 1992: New records of rare and threatened polypores in Finland. Karstenia, 32, p. 81-94.

Niemelä, T., Ryvarden, L., 1983: AntrodielLa citrinelLa: a new polypore species. Karstenia, 23, p. 26-30.

Piątek, M., 2001: The genus Antrodiella (Fungi, Poriales) in Poland. Polish Botanical Journal 46: 183-190.

Pieri, M., Rivoire, B., Gannaz, M., 2000: Antrodiella citrinella Niem. & Ryv. Polypore again for France. Quarterly Newsletter of the Mycological Federation Dauphiné Savoie Dauphine’é-Savoie 159: 45-47.

Pieri, M.; Rivoire, B., 1996: Apropos de quelques polypores (Aphyllophoromycetidae) rares ou critiques recoltes recemment. 1. Bull. Soc. mycol. France, 112, p. 163-187.

Ryvarden, L. & Gilbertson, R. L., 1993:  European polypores. Synopsis fungorum 6, Fungiflora (Oslo), 1, p. 1-387.

Vampola, P., 1991: Antrodiella parasitica, a new polypore for the Centraleuropean mycoflora. Ceska Mykol., 45, p. 150-154.

Vampola, P., 1995:  Polyporales exsiccati Cechoslovaciae, 6 (12), nr. 132.

Vampola, P., Pouzar, Z., 1996: Contribution to the knowledge cf the Central European species cf the genus Antrodiella. Czech Mycol., 49 (1), p. 21-33.

Vlasak, J., 1990: Antrodiella citrinella -novy choros pro CSFR.eska Mykol., 44, p. 238-239.

Wieners, M., Reinhard, A., Förschler, M., Scholler, M., 2016: The Rare Polypore Antrodiella citrinella and Its Special Phenology in the Black Forest National Park (Germany). J. Biodivers. Endanger. Species 2016, 4:2. DOI: 10.4172/2332-2543.1000168


Known distribution - countries

Regional Population and Trends

Country Trend Redlisted