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  • Under Assessment
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Tricholoma borgsjoeënse Jacobsson & Muskos

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Scientific name
Tricholoma borgsjoeënse
Jacobsson & Muskos
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
IUCN Red List Category
VU A2c+3c+4c
Proposed by
Tor Erik Brandrud
Tor Erik Brandrud
Thomas Læssøe
Comments etc.
Vladimír Kunca
Anders Dahlberg

Assessment Notes

Taxonomic notes

Why suggested for a Global Red List Assessment?

Tricholoma borgsjoeënse is a mycorrhizal species associated with rich/calcareous Picea abies forests, almost confined to boreal areas of Fennoscandia(-Russia?). The species is regarded as threatened in the Nordic countries, suffering e.g. from modern (clear-cut) forestry and fragmentation of older Norway spruce stands.
Preliminary global and European Red List assessment;
VU (A2c+3c+4c), with an estimated decline of >30% during evaluation period of 50 years.

The estimated decline is due to a long-term and persistent decline in mature/old-growth forests of productive Picea abies in boreal areas.

Geographic range

The species is rare but has a wide distribution in the boreal region of C-N Fennoscandia. It is also known from two, recent records of montane-subalpine spruce forest regions in C Europe (The Czech Republic, Germany). A very closely related species, T. atroviolaceum occurs in North America.

Population and Trends

Tricholoma borgsjoeënse was described as late as 2006 from Sweden, and is thus still fairly little known. Apparently, this is a northern, rare species, more or less confined to richer/calcareous, boreal Norway spruce forests. Most records are from central- and northern parts of Fennoscandia (middle- northern boreal regions). It follows the boreal spruce forest belt almost to the westcoast of C Norway. Per 2014, it is reported from 10 localities in Norway, mainly in Trøndelag(-Nordland) and some inner valleys of SE Norway. In Sweden, the species is also known from approx.. 10 localities, of which 6 are from Medelpad, C. Sweden, the district from where the species was originally described. In Finland the species is recorded from the south coast up to Lappland, but everywhere very rare. The real number of localities in Fennoscandia is estimated to approx. 400-500. The species is expected to occur also in (W) Russia, but suitable rich-calcareous spruce sites probably thins out eastwards in N Europe. More localities will probably appear also in C Europe, but these are likely to be few and small outposts of a northern distribution, to be compared with other, northern boreal spruce forest taxa in Europe, such as Cortinarius borgsjoeensis.
The species is suffering e.g. from modern (clear-cut) forestry and fragmentation of older, high-productive Norway spruce stands. There is also a considerable habitat loss of rich/calcareous, spruce forests in the Nordic countries since the calcareous areas often are small, already naturally fragmented, and situated in urbanized areas. Calcareous spruce forests are redlisted as VU in Norway, and these forests are regarded as declining in the same magnitude in Sweden. Altogether, we estimate that the mature/old-growth stands of rich/calcareous spruce forests have had a decline of >30% in Fennoscandia over 50 years.
Tricholoma borgsjoeënse is redlisted as VU (C2a(i) in Norway, and as VU (A2c+3c+4c; C1+2a(i) in Sweden. In Finland as NT (B2 a,b (iii) (iv) + D2) in Finland.

Preliminary global and European Red List assessment;
VU (A2c+3c+4c + C2a(i)?), with an estimated decline of >30% during evaluation period of 50 years.

Population Trend: Decreasing

Habitat and Ecology

The species occurs in rich low-herb spruce forests, or calcareous spruce forests, often in mossy, mesic to seasonally hydrophilous sites, is mainly associated with older spruce forest stands, without influence of modern forestry with clear-cuts.


The species is threatened by loss, depauperation and fragmentation of intact, mature Picea abies forest habitat, due mainly to intensive forestry with clear-cuts. The species seems, especially in northern areas, to suffer from re-establishment in production forests with a (clear-cut) turnover period of less than ca 80-100 years.

Conservation Actions

To prevent decline and fragmentation of rich spruce forests with good habitat quality, it is important to set aside reserves with productive coniferous forests. It is furthermore important to establish woodland key biotopes and similar kinds of forest stand where a non-intensive, closed cutting is performed, leaving much of the stand qualities intact, including a continuity in the spruce roots and their mycorrhizae.

Research needed

Population dynamics, with emphasise on the species needs for old-growth forests, as well as the response to small scale forestry with closed cutting should be further studied. There is a need for further mapping/surveying of the species, especially in Russia(-Balticum), but also in the outpost areas of C Europe.

Use and Trade


Brandrud, T.E. 2013. Rødlistede og sjeldne musseronger (Tricholoma spp.) har internasjonalt viktige populasjoner i Norge/Norden. Agarica 33: 57-72. 
Christensen M, Heilmann-Clausen J, 2013 The Genus Tricholoma (Fungi of Northern Europe 4). Danish Mycological Society, Svampetryk, 228 pp.
Holec J, Kriz M, 2012. Tricholoma borgsjoeënse found in the Czech Republic and Tricholoma luridum documented in Slovakia. Czech Mycology 6 (2): 223–232.
Jacobsson S, Muskos S, 2006. Borgsjömusseron, Tricholoma borgsjoeënse, en nybeskriven art från Medelpad. Sv. Mykol. Tidsskr. 27(3): 66-70.

Known distribution - countries

Regional Population and Trends

Country Trend Redlisted