Assessment Notes

Justification

Mycena overholtsii is a common 'snowbank' species known from the western North American mountains, and from Quebec in eastern North America. Even though most snowbank fungi are suffering a loss of habitat due to climate change, this species stands out because of the widespread distribution as it is not restricted to the western North American mountains. Considering this, and the large number of reported occurrences it is assessed as Least Concern (LC).

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Geographic range

Mycena overholtsii is recorded widespread across the Sierra Nevada, Cascade Range and Rocky Mountains in western North America. It is also know from Quebec, and likely occurs in interconnected boreal forests.

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Population and Trends

The population is widespread, and it is a very common species in appropriate habitat. In western North America, it is confined to high elevation forests with large woody debris, and an ample winter snowpack. These forests are affected by changing climate; with warmer and drier winters that have elevated and lessened the average snowfall. Stoelinga et al. (2010) state that Cascade Range spring snowpack declined 23% during 1930-2007, and models suggest that the rate of snowpack decline with increase substantially by the end of the century (Rhoades et al. 2018). Little is known about the eastern North American subpopulations, including how widespread it is.

Mycena overholtsii will experience a continued loss and decline of appropriate habitat in parts of its range, but due to the widespread nature, and number of subpopulations, it will likely be at a relatively low percentage for the overall population.

Population Trend: Decreasing

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Habitat and Ecology

Typically it is found fruiting in large clusters, more rarely in small tufts or solitarily, fruiting on the edges of melting snowbanks in spring and summer in the western United States. Habitat specifics for eastern North American subpopulations are not well known. It is saprotrophic, occurring on conifer (especially Abies) stumps, logs and woody debris.

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Threats

In western North America, this species is dependent on thick winter snowpacks and large logs or stumps to fruit. Snowbank fungi, which most are unique to the western North American mountains, occur/fruit in areas with ample snowpack. They fruit in the spring and summer, as the snow melts and recedes. As the climate changes, warmer and drier winters have elevated and lessened the average snowfall. Climate change, continued loss of habitat due to logging, decline in area of old growth forests, and hotter, stand replacing fires are probably detrimental to this species.

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Conservation Actions

This species is included on the United States Forest Service Northwest Forest Plan Survey and Manage list of rare/old growth forests dependent fungi, and has been actively surveyed for since the late 1990’s (Castellano et al. 1999). A better understanding of habitat requirements and population extent of the species in eastern North America is needed.

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Use and Trade

No use/trade is known.

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Source and Citation

Siegel, N. & Mueller, G.M. 2025. Mycena overholtsii. The IUCN Red List of Threatened Species 2025: e.T198479661A198487037. Accessed on 22 November 2025.

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• Country occurrence