Described from a collection made at Mount Rainier National Park, in Washington, USA (Smith 1960).

Many western North American Tricholomopsis species remain poorly known, and diversity and species borders should be investigated.

Tricholomopsis fulvescens is a rare and poorly known species with an orange-yellow cap covered in appressed tawny fibrils, yellow gills, and a yellow-brown stem which darkens to rusty-brown where handled.

Despite being surveyed for on US Forest Service and Bureau of Land Management lands in the Pacific Northwest and northern California since the late 1990’s, there have only been three collections made in this period (Mycoportal 2021).

Currently known from nine collections from eight locations; four of which are historic collections.

Scattered disjunct populations are known from the Cascade Range in Washington and Oregon, USA, with a single site in the Klamath Range in California. Also reported from Arizona; these collections should be verified, and are being excluded from this assessment.

Too few collections of this species have been made to characterize its habitat preferences, but it appears to prefer old growth forests, (which in turn have lots of course woody debris). No Pacific Northwest collections have been reported in the past 25 years, despite being included on the Northwest forest plan Sensitive Species list, and actively surveyed for (Castellano et al. 1999).  Efforts have been made to relocate it at two of the historic Washington populations (field visits 2014, 2017-2020 by N. Siegel).

Saprobic. Solitary or scattered on rotten conifer wood in mid to high elevation forests. A poorly known species with limited knowledge of habitat preference, other than most collections come from old growth forests. Fruiting in fall.

Too little is known about this species to make a robust assessment of possible threats, but high-intensity fires that consume large pieces of coarse woody debris likely result in a lack of appropriate substrate and habitat.

Until more is known about this species habitat restraints, no specific conservation actions can be identified with regards to this species.

Targeted surveys for this species. Better understanding of habitat restraints. Modern taxonomic work on Tricholomopsis in the Pacific Northwest.

None known.

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.

MyCoPortal. 2021. http://mycoportal.org/portal/index.php. Accessed on February 03.

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.

Smith, A. H. 1960. Tricholomopsis (Agaricales) in the Western Hemisphere. Brittonia 12: 41–70.