Assessment Notes

Justification

This species is currently known from ten sites in California, and five in Oregon. However, modern taxonomic work and targeted surveys are needed to identify habitat preferences and trends of this species. Although not commonly reported, the species occurs scattered, but relatively evenly distributed from central California to Oregon. Given the broad range from south to north, it can be estimated that it occurs in many more sites over its range and that the population size is above the threshold for triggering an assessment under criterion C. Even so, the decline in habitat quality over the past 40-50 years due to an increase in fire intensity is likely negatively impacting the species population size so the species should be monitored. Currently it is assessed as Least Concern.

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Taxonomic notes

This species was described from a collection made in Jackson County, Oregon (Trappe and Castellano 2000).

The genus Gastroboletus accommodates a number of species with semisequestrate to sequestrate fruitbodies. These morphological forms have evolved multiple times, within different genera of boletes. Some of these species have been transferred to their ancestral genera, whiles others remain in limbo. Preliminary data show that G. amyloideus and G. vividus form a closely-knit group with Boletus smithii (J. Frank pers. comm), and more work is needed to delimit species concepts.

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Geographic range

This species is scattered in high elevation forest of the Sierra Nevada mountain range of California, USA, and the Cascade Range in California and southern Oregon.

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Population and Trends

This species is uncommonly reported. It is currently known from fifteen sites; ten of which are in California, in high elevation forests. Data are limited, but it is possibly restricted to mature and old growth forests. More work is needed to identify habitat preferences and trends of this species. Although not commonly reported, the species occurs scattered, but relatively evenly distributed from central California to Oregon. Given the broad range from south to north, it can be estimated that it occurs in many more sites over its range. The decline in habitat quality over the past 40-50 years due to an increase in fire intensity likely is negatively impacting the species population size.

Population Trend: Decreasing

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Habitat and Ecology

This species is solitary, scattered or found in small clusters; fruitbodies form underground, typically remaining buried, or occasionally erupting from duff when mature. It is ectomycorrhizal, associated with Pinaceae, especially Red Fir (Abies magnifica), Lodgepole Pine (Pinus contorta) and Mountain Hemlock (Tsuga mertensiana) in high elevation forests. This species is possibly restricted to mature and old growth forests. Fruiting is in summer and early fall, typically after monsoon rains.

This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal.

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Threats

Prolonged droughts and decades of fire suppression have drastically altered the high sierra forest, leading to thicker, denser, Abies dominated forest. As a result, hotter, stand replacing fires (rather than patchwork and understory burns) are commonplace, altering appropriate habitat drastically, and making it ill-suited for this species.

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Conservation Actions

It will be important to protect known sites from management activities, including logging, fuel reduction, or other development and disturbance. Targeted surveys are needed in the Sierra Nevada in California. Modern taxonomic work is also needed on this species, to delimit species concepts with Gastroboletus amyloideus and Boletus smithii.

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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. Gastroboletus vividus. The IUCN Red List of Threatened Species 2025: e.T272184100A272184641. Accessed on 23 November 2025.

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• Country occurrence