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Hygrophorus caeruleus O.K. Mill.

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Scientific name
Hygrophorus caeruleus
Author
O.K. Mill.
Common names
 
IUCN Specialist Group
Mushroom, Bracket and Puffball
Kingdom
Fungi
Phylum
Basidiomycota
Class
Agaricomycetes
Order
Agaricales
Family
Hygrophoraceae
Assessment status
Assessed
Preliminary Category
LC
Proposed by
Noah Siegel
Assessors
Noah Siegel
Comments etc.
James Westrip

Assessment Notes

Justification

Hygrophorus caeruleus is a medium-sized mushroom, typically buried under duff, fruiting in spring and early summer. Recognized by the silvery blue, bluish gray to bluish green color, short, stocky stature and often strong, rancid-farinaceous odor.

Currently reported from ~30 sites over a widespread area, and due to it’s often cryptic fruiting habit (under duff), likely highly under reported. Data to assess trends is lacking, but there are a number of recent reports. Considering these factors, I recommend listing as Least Concern (LC).


Taxonomic notes

Described base on a collection made near McCall, Idaho, USA (Miller 1984). Recent genetic analysis has shown close affinity with Clitocybe sensu lato, and it likely will get transferred to Clitocybe or a segregate genus in the near future.


Why suggested for a Global Red List Assessment?

Hygrophorus caeruleus is a medium-sized mushroom, typically buried under duff, fruiting in spring and early summer. Recognized by the silvery blue, bluish gray to bluish green color, short, stocky stature and often strong, rancid-farinaceous odor.

Currently reported from ~30 sites over a widespread area, and due to it’s often cryptic fruiting habit (under duff), likely highly under reported. Data to assess trends is lacking, but there are a number of recent reports. Considering these factors, I recommend listing as Least Concern (LC).


Geographic range

From the southern Sierra Nevada mountains in California north through the Cascade Range into Washington, and east into the northern Rocky Mountains. Typically in drier forest habitat.


Population and Trends

Population is widespread in the western mountains; currently known from ~30 sites. The often cryptic growth (buried under duff) makes this species hard to find; but because of the blue colors and bad smell, it rarely goes unreported if found. Not enough data exist to assess trends, but based on what is known about the habitat preferences, it is likely stable.

Population Trend: Stable


Habitat and Ecology

Solitary, scattered, or in small clusters; typically buried under duff and litter. In California, it seems to prefer White Fir (Abies concolor) forest; but can be found in duff under most conifers. Unless it is growing in an area with hard packed soil, and limited duff, it is rarely exposed; but it will push up the duff, forming “shrumps”. Fruiting in spring, soon after snowmelt, continuing into summer. Nutritional mode not known (Siegel et al. 2019)

The often buried fruitbodies and strong odor are suggestive of a species that is, at least somewhat dependent on mycophagy (primarily eaten by small mammals) for spore dispersal. Wind dispersal is probably still important, but to a lesser extent. (Siegel 2017).

Temperate Forest

Threats

Prolonged droughts and decades of fire suppression have drastically altered the high Sierra forests, leading to thicker, denser Abies-dominated forest. As a result, hotter, stand-replacing fires (rather than patchwork and understory burns) are commonplace, altering appropriate habitat drastically, burning much of the available large woody debris apparently necessary for this species’ habitat. Climate change, leading to a reduction in snowpack in the western North American mountains has limited suitable habitat for this species; which only appears to occur after wet winters.

Increase in fire frequency/intensityHabitat shifting & alterationDroughtsOther impacts

Conservation Actions

This species was included on the US Forest Service Northwest Forest Plan species of special concern (Castellano et al. 1999).


Research needed

Recent genetic analysis has shown close affinity with Clitocybe sensu lato, additional work on genera placement is needed.

Taxonomy

Use and Trade

None known.


Bibliography

Castellano, M., Smith, J.E., O’Dell, T., Cázares, E. and Nugent, S. 1999. Handbook to Strategy 1 Fungal Species in the Northwest Forest Plan. General Technical Report PNW-GTR-476. United States Department of Agriculture.

Miller, O.K. 1984. A New Species of Hygrophorus from North America. Mycologia 76(5): 816-819

Siegel, N. 2017. USFS Species profile: Hygrophorus caeruleus. Internal Forest Plan Document, unpublished.

Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. and Ikeda, D. 2019. A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.


Country occurrence

Regional Population and Trends

Country Trend Redlisted