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Cortinarius eucaeruleus Rob. Henry

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Scientific name
Cortinarius eucaeruleus
Rob. Henry
Common names
Schönblauer Klumpfuß
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Assessment date
IUCN Red List Category
Brandrud, T.-E.
Kałucka, I.L. & Iršėnaitė, R.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/147163295/147833459


The European/global population is estimated to 1,700 localities/sites. This is equivalent to 34,000 mature individuals. The decline of the species major habitat, calcareous Quercus-Carpinus forests in the evaluation period (last 50 years or three generation) is estimated to be in the magnitude of 15-20% (a similar decline also estimated for other, relevant habitats; Tilia-Corylus forests). Based on this, the species becomes red listed as NT according to the A-criterion (A2c + 3c + 4c) (species/habitat decline >15%).

Taxonomic notes

The species is characteristic and easy identifiable, due to its initially striking bright violaceous blue cap. However, some older collections/finds can be difficult to interpret due to former, different name usage. Many are still labelled C. terpsichores, some old are labelled C. caerulescens).

Geographic range

The species is rare but widely distributed within the European range of Carpinus-Quercus forests; known from France east to the Stavropol Krai (Causasus N) in SW Russia. It occurs north to the boreonemoral, southern part of Scandinavia and Estonia (in calcareous Tilia or Corylus forests), and south to montane Carpinus-Quercus forests in the mediterranean region. Due to present knowledge on the species itself, and the distribution of its habitat, this seems to be a more or less strictly European species (possibly including Turkey).

Population and Trends

Due to former mixing of names in the group (the names C. terpsichores and C. coerulescens often applied formerly), the number of known localities from temperate W and C Europe is not precise, but is estimated to be approx. 50 (eight sites confirmed from Hungary, also newly published from Poland - Ślusarczyk et al. 2015). The total number in W-C Europe is estimated to 50 x 20 = 1000 localities. 

In E and SE Europe including SW Russia, the number of verified occurrences in is very little known. The total number here estimated to be somewhat lower than in W and C Europe based on the distributional range of Carpinus-Quercus forests; 500 localities. 

In Scandinavia, the species is known from approx 20 sites/localities. The real, total number is here estimated to 200 sites/localities. 

The European/global population then adding up to 1,700 localities/sites. This is equivalent to 34,000 mature individuals according to IUCN standards (Dahlberg and Mueller 2011). The decline of the calcareous Quercus-Carpinus forests in the evaluation period (last 50 years) is estimated to be in the magnitude of 15-20%. Based on this, the species could be listed as NT according to the A-criterion (A2c + 3c + 4c) (species/habitat decline >15%).

Population Trend: decreasing

Habitat and Ecology

Cortinarius eucaeruleus is a mycorrhizal associate of Carpinus betulus, Corylus avellana, Quercus spp. and Tilia cordata. The species is found mainly in temperate/nemoral, calcareous Carpinus-Quercus forests, but also in boreonemoral outposts of calcareous Tilia-Corylus and Quercus-Corylus forests/woodland meadows. Sometimes reported from calcareous Fagus forests, but then probably with Quercus or Carpinus present.


Cortinarius eucaeruleus and its habitats (calcareous Carpinus-Quercus-Tilia-Corylus forests) are threatened by (i) area loss due to urban/settlement expansion, lime quarries, etc, and (ii) lowered habitat quality/ecological conditions due to forestry, invasive plants and eutrophication (rise of Nitrogen levels mainly by local and transboundary air pollution and fertilisers). In some areas also the change of management practices (ceased grazing) has had negative effects. The European area of oak forests has according to statistics decreased by 20%. There are also national evidences for a stronger decline; for instance the area of calcareous Tilia forests in Norway has decreased by >50% since 1970 (Hansen and Delatour 1999, Denman et al. 2014).

Conservation Actions

To prevent areal decline and further fragmentation of calcareous Carpinus-Quercus-Tilia forests with good habitat quality, it is important to set aside reserves on calcareous hotspots, housing many rare/redlisted, habitat-specific species such as Cortinarius eucaeruleus, C. odoratus, C. alcalinophilus and C. prasinus. It is furthermore important to establish also sites with a less strict conservation regime, such as woodland key biotopes, where some non-destructive human activity can be accepted (such as non-intensive, closed cutting).

Research needed: More mapping/surveying and monitoring of C. eucaeruleus are needed. First and foremost more data on occurrences in calcareous Carpinus-Quercus forests of E and SE Europe are needed. These are per date only little mycologically surveyed. Secondly, it would also be very advantageous to have established monitoring series in this habitat. Data that can document time trends on C. eucaeruleus and co-occurring habitat-specific fungi are completely lacking. Finally, more documentation on the degree of decline of the habit itself is needed.

Use and Trade

The species is not used.

Source and Citation

Brandrud, T.-E. 2019. Cortinarius eucaeruleus. The IUCN Red List of Threatened Species 2019: e.T147163295A147833459. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T147163295A147833459.en .Accessed on 2 February 2024

Country occurrence