Assessment Notes

Justification

Hygrophorus calophyllus is an easily recognizable, robust fungus with salmon-red coloured gills. In Europe, the species is a indicator species of old, calcareous conifer forests which have high conservation values and a rich fungal biodiversity. It has a sparse circumboreal distribution with less than 100 known localities. The total population size is estimated not to exceed 2,500 mature individuals. Due to forestry, the number of localities is suspected to have declined with more than 50% and continue to decline. Hence, H. calophyllus is assessed as Endangered (EN) under criterion A2c+3c+4c, due to population reduction of more 50% in 50 years (three generations), and under C1 (small population size and suspected continuing decline with under 2,500 mature individuals).

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Geographic range

Hygrophorus calophyllus has a circumboreal distribution. It is very rare and has a fragmented occupancy. The core population in Europe is located in Sweden and Norway. It has a few records from central Europa and North America. Reported occurrences in Italy and Japan have not been confirmed.

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Population and Trends

Hygrophorus calophyllus is currently known from about 85 localities of which 50 are located Europe (predominantely in), and 35 localities in North America.

The total number of localities, including yet unrecorded sites, is suspected not to exceed 200, due requirement of particular habitat type. The total population size is estimated not to exceed 2,500 mature individuals. The species is very rare in throughout the boreal and only have a few records in the temperate zone. This species is suspected to have declined during the last 50 years in Europe, due to loss of habitat area and reduced habitat quality caused by forestry (logging) (cf. Kotiaho 2017, Svensson et al. 2019). Similar habitat decrease has taken place and is going on in North America.

The habitats of H. calophyllus are small in area and those are threatened in many countries in Northern Europe (e.g. Brandrud and Bendiksen 2018). The same trend has been reported from North America with similar population/habitat decline and is due e.g. continued loss of habitat, decline in old growth forest areas, and replacing fires are likely detrimental to this species (Siegel 2017). 

The species is estimated to have decreased by more than 50% in three generations and the decline (50 years, Dahlberg and Mueller 2011) based on habitat-loss of old-growth forests on calcareous soils and continuing decline, but the number of localities is very low with ca 50 known localities in Europe (eg. Sweden 10-20; Norway 15-20; Russia 5, Croatia 1). USA with 35 (Siegel 2019). The species has been evaluated as threatened in Norway (EN), Sweden (EN) and Croatia (CR). It is reported as regionally extinct (RE) from Finland (von Bonsdorff et al. 2019) as last collected in 1889.

Population Trend: Decreasing

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Habitat and Ecology

Hygrophorus calophyllus forms ectomycorrhiza with Scots Pine (Pinus sylvestris) and Norway Spruce (Picea abies) in Europe and other Pinaceae in North America. The species grows in old conifer forests on calcareous soils (dry-mesic eutrophic herb-rich forests) in Europe (von Bonsdorff et al. 2019, Kytövuori et al. 2005, Larsson et al. 2010). This habitat type is identified to have a high conservation value, including a rich fungal biodiversity (von Bonsdorff et al. 2014, Bjørndalen 2003, Nitare 2011). This kind of habitat type is naturally very small in area and fragmented and it has been assessed as threatened (VU-EN) in Finland and in Norway (Kouki et al. 2018, von Bonsdorff et al. 2014, Artsdatabanken 2018). The habitat type has also been decreasing in area and habitat quality in the other Nordic Countries (e.g. Nitare 2011, Brandrud and Bendiksen 2018).

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Threats

Due to logging, old growth forests on calcareous soils is a threatened habitat with reduced area and a declining number forests (Kouki et al. 2005, Nitare 2011, von Bonsdorff et al. 2014). Old-growth forests has been logged for timber and to some extent transformed to fields.

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Conservation Actions

Old-growth conifer forests on calcareous soils should be protected, as they are hot spots for Hygrophorus calophyllus and many for other fungi.

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Use and Trade

The species is not known to be used.

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Source and Citation

von Bonsdorff, T. 2019. Hygrophorus calophyllus (amended version of 2019 assessment). The IUCN Red List of Threatened Species 2019: e.T147323011A159881386. Accessed on 20 November 2025.

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• Country occurrence