Assessment Notes

Justification

Mycetinis applanatipes is known from high elevation forests in the Sierra Nevada and Cascade Range, in California and into central Oregon. There has been a single highly disjunct report from British Columbia, Canada which needs to be critically compared with California and Oregon records, and this is excluded from this assessment. Currently, the species is known from 10 disjunct sites over a widespread area. This species has been surveyed as part of the Northwest Forest Plan since the late 1990's, but despite this, only six collections have been made in that time. Two known sites in California were machine thinned, and it has not been found since at these localities (D. Desjardin pers. comm.). Estimating that there could be a maximum of 200-500 localities for this species, based on suitable habitat, each with 4-8 mature individuals, results in a very conservative estimate of 8,000-40,000 mature individuals in scattered relatively small subpopulations, each of which may contain 1,000 or more mature individuals. Thus, taking a conservative approach, the species is assessed as Near Threatened C2a(i).

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Geographic range

This species is known from high elevation forests in the Sierra Nevada and Cascade Range of California into central Oregon (MyCoPortal 2024). There is a single highly disjunct report from British Columbia, Canada; this collection should be critically compared with California and Oregon records and is excluded from this assessment.

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Population and Trends

Currently, it is known from 10 disjunct localities over a widespread area. This species has been surveyed as part of the Northwest Forest Plan (Castellano et al. 1999) since the late 1990's. Despite this, only six collections have been made in that time. Vast areas of appropriate substrate are found in the California mountains, but other factors determining suitable habitat are unknown. Fruiting periodicity is unknown, and data regarding other life history traits relevant to dispersal are also lacking. Two known sites in California were machine thinned, and it has not been found since at these sites (D. Desjardin pers. comm.). Taking a precautionary approach, estimating that there could be a total of 200-500 sites based on suitable habitat, each with 4-8 mature individuals, results in a very conservative estimate of 8,000-40,000 mature individuals in scattered, relatively small subpopulations.

Population Trend: Decreasing

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Habitat and Ecology

It is a saprobic species. It fruits as scattered to gregarious growths, often in small fused clusters on conifer duff and needles. Most collections come from Red Fir (Abies magnifica) forest. It is typically found in high elevation forests above 2,000 m.

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Threats

Large scale disturbances like logging or machine thinning are likely to be detrimental. More basic biodiversity data for this species need to be gathered to know what other threats are negatively impacting the species.

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Conservation Actions

This species is included on the United States Forest Service Northwest Forest Plan Survey and Manage list (as Marasmius applanatipes) of rare/old growth forests dependent fungi, and has been actively surveyed for since the late 1990’s (Castellano et al. 1999). Logging and machine thinning in, and near, known sites should be limited. Detailed habitat information is needed to properly assess the geographic range and habitat preferences of this species; in addition to studies into its long term responses to disturbances due to logging as well as to low to high intensity fires.

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Use and Trade

No use/trade is known.

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Source and Citation

Mueller, G.M. & Siegel, N. 2025. Mycetinis applanatipes. The IUCN Red List of Threatened Species 2025: e.T273227384A273243727. Accessed on 22 November 2025.

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• Country occurrence