Described from Wyoming, USA (Smith & Solheim 1953).
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; not restricted to the western North American mountains.
Considering this, and the number of occurrences, I recommend listing as Least Concern (LC).
Widespread across the Sierra Nevada, Cascade Range and Rocky Mountains in western North America. Also know from Quebec, and likely to occur in interconnected boreal forest.
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). Mycena overholtsii will experience a continued loss and decline of appropriate habitat, but due to the widespread nature, and number of populations, at a low percentage for the overall population.
Little is known about eastern North American populations, and how widespread it is.
Population Trend: Decreasing
Typically fruiting in large clusters, more rarely in small tufts or solitary, fruiting on the edges of melting snowbanks in spring and summer. Saprotrophic, occurring on conifer (especially Abies) stumps, logs and woody debris.
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, decline in area of old growth forests, and hotter, stand replacing fires are likely detrimental to this species.
Snowpack decline in the western North American mountains has been well documented (Mote et al. 2005, Mote et al 2018, Zeng et al. 2018, Stoelinga et al. 2010). 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).
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 in eastern North America.
Castellano, M.A., Smith, J.E., O’Dell, T., Cázares, E. and Nugent, S. 1999. Handbook to Strategy 1 Fungal Species in the Northwest Forest Plan. U. S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR. 195 p.
Fyfe, J. C. et al. 2017. Large near-term projected snowpack loss over the western United States. Nat. Commun. 8, 14996 doi: 10.1038/ncomms14996.
Mote, P.W., Hamlet, A.F., Clark, M.P. and Lettenmaier, D.P. 2005: Declining mountain snowpack in western North America. Bulletin of the American Meteorological Society 86, 39–49.
Mote, P.W., Li, S., Lettenmaier, D.P. et al. 2018. Dramatic declines in snowpack in the western US. npj climate and atmospheric science 1, 2 (2018). https://doi.org/10.1038/s41612-018-0012-1
MyCoPortal. 2021. Mycology Collections Portal. Available at: http://mycoportal.org
MycoQuebec. 2021. https://www.mycoquebec.org/bas.php?l=r&nom=Mycena overholtsii / Mycène d’Overholts&post=Mycena&gro=28&tag=Mycena overholtsii
Rhoades, A.M., Jones, A.D. and Ullrich, P.A. 2018. The Changing Character of the California Sierra Nevada as a Natural Reservoir. Geophysical Research Letters. DOI: 10.1029/2018GL080308
Siegel, N. 2017. United States Forest Service R5 rare species assessment. Draft internal document.
Smith, A.H. and Solheim, W.G. 1953. New and Unusual Fleshy Fungi from Wyoming. Madroño 12: 103-109.
Stoelinga, M.T., Albright, M.D. and Mass, C.F. 2010. A new look at snowpack trends in the Cascade Mountains. Journal of Climate 23: 10. 2473–2491. https://doi.org/10.1175/2009JCLI2911.1