Amylocystis lapponica

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***Amylocystis lapponica*** (alternatively spelled ***Amylocystis lapponicus***) is a species of bracket fungus in the family Fomitopsidaceae, and the type species of genus *Amylocystis*. It produces medium-sized, annual fruit bodies that are soft, and have a strong, distinct smell. The fungus is a saprophyte that feeds on coniferous wood of logs lying on the ground, and causes brown rot. It is a rather rare species that only occurs in old-growth forest.

## Taxonomy

The fungus was originally described by Swedish mycologist Lars Romell in 1911, who called it *Polyporus lapponicus*. The type collection was made in Nattavaara (Sweden), where it was found growing on fir. Romell initially thought the fungus might be *Climacocystis borealis*, but ultimately rejected that opinion, as that species has an easily breakable fruit body, and its spores are of different size and shape.

*Amylocystis lapponica* has been shuffled to several different polypore genera in its taxonomic history, including *Ungulina* (Pilát, 1934), *Leptoporus* (Pilát, 1938), and *Tyromyces* (J.Lowe, 1975). The fungus has microscopic characteristics that are typical of the genus *Tyromyces*, but differs by the presence of thick-walled amyloid cystidia in the hymenium. For this reason, A. Bondartsev and Rolf Singer created the genus *Amylocystis* in 1944 to contain the fungus. *Polyporus ursinus*, proposed by Curtis Gates Lloyd in 1915, is now considered a synonym of *Amylocystis lapponica*.

## Description

The fungus has fruit bodies that range in form from crust-like to effused-reflexed (mostly crust-like, with edges curling out to form rudimentary caps). Individual fruit bodies measure up to Template:Convert wide, and have a dirty whitish to light buff surface colour that becomes reddish brown when dry or if bruised.

*Amylocystis lapponica* has a monomitic hyphal system, containing only generative hyphae. These hyphae are mostly thick-walled and measure 4–10.5 µm thick. The spores are cylindrical, hyaline, and smooth, measuring 8–11 by 2.5–3.5 µm. They are unreactive in Melzer's reagent.

*Oligoporus fragilis* is similar in appearance, but can be distinguished microscopically from *Amylocystis lapponica* by the lack of amyloid cystidia.

## Habitat and distribution

*Amylocystis lapponica* decomposes fallen conifer wood, in which it causes brown rot. Its preferential hosts are spruce and larch, although it is occasionally found on fir. It has a circumboreal distribution in coniferous forests. In Europe, the fungus is restricted almost exclusively to old-growth forests. Several conditions are required to support local populations, including: "vegetative continuity (never cut), natural tree species composition, multi-aged structure, rich presence of dead wood in various stages of decay, relatively large area of virgin forest surrounded by near-natural forest, and a stable, cold and humid meso- and microclimate." Because of this requirement the species is rare. For example, in the Czech Republic, despite the long and intensive history of polypore study in that area, *A. lapponica* has only been recorded from the Boubínský prales virgin forest, even though there are other old-growth forests in the country. Similarly, in Poland it is known only from Białowieża Forest (Białowieża National Park). Both the Czech and Polish locations have a similar management history–"minimal influence by man".

In contrast to its rarity in Central and Southern Europe, *A. lapponica* is known from hundreds of localities in Finland and Sweden, and dozens in Norway. Here the fungus is used as an indicator species to help evaluate areas in need of conservation. The fungus is widely distributed in western North America. It is also found in China.

In Europe, the fungus has been recorded from 12 countries, and is red-listed in 7 countries. In 2004, *Amylocystis lapponica* was one of 33 species proposed for protection under the Bern Convention by the European Council for Conservation of Fungi. In both the Czech Republic and Poland, where it is considered critically endangered, the fungus is found on their Regional Red Lists and as such is protected by law.

The discomycete *Hyaloscypha epiporia* grows only on the surface of old polypores fruiting on softwood, and is often found on old, partly decayed fruit bodies of *Amylocystis lapponica*.

## References

1. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Rommell 1911`
2. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Pilát 1934`
3. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Pilát 1938`
4. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Lowe 1975`
5. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Singer 1944`
6. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Lloyd 1915`
7. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Species Fungorum synonymy: Amylocystis lapponica`
8. ↑ 8.0 8.1 8.2 8.3 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Ryvarden 2014`
9. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Domański 1972`
10. ↑ 10.0 10.1 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Holec 2007`
11. ↑ 11.0 11.1 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Dahlberg 2006`
12. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Bredesen 1997`
13. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Rosok 1998`
14. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Ginns 2017`
15. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Dai & Penttilä 2005`
16. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Huhtinen 1989`

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