Assessment Notes

Justification

Suillus quiescens is a widespread but rarely reported species in California and Oregon. It is currently known from fruit body records from about 15 localities, and a few records  from root tip sequences and environmental samples. However, based on the wide distribution and the likelihood of it being under-reported (due in part to misidentifications) is is assessed as Least Concern (LC).

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Taxonomic notes

Suillus quiescens was described from collections made in California, USA (Bruns et al. 2010).

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Geographic range

Currently this species is known from disjunct subpopulations in Califronia and Oregon, USA; from the Channel Islands in the south, eastern Sierra Nevada in the east, and central Oregon coast in the north. This species is a recent description and commonly misidentified as Suillus brevipes, and as such its distributional limits are not yet fully clear. Based on known habitat, it is likely far more widespread than currently known. It has been introduced to New Zealand, where it grows with the non-native Pinus radiata.

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Population and Trends

The population is widespread, but may be an infrequent fruiter in many areas, and may be present in areas as a spore bank in the soil (Bruns et al. 2010). Currently it is known from around 15 fruiting localities (Mushroom Observer 2021, iNaturalist 2021), but it is expected to be more common than currently reported. Data to assess trends of this species are lacking.

Population Trend: unknown

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Habitat and Ecology

It is ectomycorrhizal with two- and three-needle pines, especially young Pinus muricata and P. radiata. It also occurs with P. contorta on the northern California and the Oregon coast, and based on environmental samples it is likely to occur with P. ponderosa and P. jeffreyi as well. Suillus quiescens may be an infrequent fruiter in many areas, and may be present in areas as a spore bank in the soil (Bruns et al. 2019), colonizing pine seedlings post forest fires. More data are needed on the ecology of this species. This species may be persistent in a soil spore bank, growing with pine seedlings and fruiting with young pines following forest fires or other disturbance.

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Threats

Native stands of Pinus radiata and P. muricata are under threat from development and a change in fire regimes. Pinus ponderosa has suffered die-back from drought stress in the Sierra Nevada foothills. However, these threats are likely at a scale that has not drastically affected  the overall population of this species.

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Conservation Actions

There is a general need to protect and manage coastal Pinus muricata and P. radiata forests in California, as both species are threatened. There is a need to track population trends and gain a better understanding of ecology of this species.

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Use and Trade

This species is edible, and it and closely-related Suillus are occasionally indiscriminately collected for food.

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Source and Citation

Siegel, N. 2022. Suillus quiescens. The IUCN Red List of Threatened Species 2022: e.T198478970A198487883. https://dx.doi.org/10.2305/IUCN.UK.2022-1.RLTS.T198478970A198487883.en .Accessed on 4 August 2024

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• Country occurrence