This species was described from a collection made at Yuba Pass in Sierra County, California, USA (Thiers and Trappe 1969).

 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 Gastroboletus amyloideus and G. vividus form a close-knit group with Boletus smithii (J. Frank pers. comm.). More work is needed on these species to delimit species concepts.

Gastroboletus amyloideus is a species known from approximately 30 collections from ten sites in the high elevation forests on the Sierra Nevada and southern Cascade Range in California and Oregon. Only 10 collections have been made since 1984, but more data are needed, and historic sites need to be revisited as the decline in reports coincides with a reduction in collection intensity. Thus, while it is difficult to confidently assess the impact of the lower collecting effort over the past 40 years, taking a precautionary approach, the population size is cautiously estimated at 1,000-2,000 mature individuals, with the largest subpopulation containing 750-1,500 mature individuals. Sierra Nevada forests have undergone significant changes over the past 40 years due to insect damage, drought, and wildfires and the population of G. amyloideus is suspected to have declined between 30-49% over its past three generations with declines continuing into the near future. The species is assessed as Vulnerable.

This species is known from high elevation forests in the Sierra Nevada mountains of California, USA, north into the southern Cascade Range in southern Oregon.

Currently this species is known from approximately 30 collections, from ten sites (nine of which are in California), and only ten collections have been made since 1984 (Siegel et al. 2019, iNaturalist 2024, MyCoPortal 2024). However, it is unknown how much of this the drop off in collections is from a decline in this species versus because the primary collectiors, H.D. Thiers and W. B. Cooke, are no longer collecting in the California mountains (MyCoPortal 2024). While it is difficult to confidently assess the impact of the lower collecting effort over the past 40 years, taking a precautionary approach, the estimated population size it is cautiously estimated at 1,000-2,000 (100-200 sites each with up to 10 mature individuals). Approximately 75% of the population is estimated to occur in the Sierra Nevada part of its range, which is treated here as one subpopulation; thus the largest subpopulation could be said to contain 750-1,500 mature individuals.

Sierra Nevada forests have undergone significant changes over the past 40 years and historic sites should be revisited and appropriate habitat surveyed and Steel et al. (2023) report that 30% of the region's conifer forest extent transitioned to non-forest vegetation during 2011–2020 due to insect damage, drought and wildfires and the population of G. amyloideus is suspected to have declined between 30%-49% over its past three generations (50 years) with declines continuing into the near future.

This species is solitary, scattered or in small clusters; fruitbodies forming underground, typically remain buried, or occasionally emerge from duff when mature. It is ectomycorrhizal, associated with Pinaceae, especially Red Fir (Abies magnifica) and Lodgepole Pine (Pinus contorta) in high elevation montane forests in the Sierra Nevada and Southern Cascade Range. Fruiting occurs in summer (following monsoonal rains) and fall (Siegel et al. 2019). This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal.

Sierra Nevada forests have undergone significant changes over the past 40 years and Steel et al. (2023) report that 30% of the region's conifer forest extent transitioned to non-forest vegetation during 2011–2020 due to insect damage, drought and wildfires. Prolonged droughts and decades of fire suppression have drastically altered the high Sierra Nevada forests, leading to thicker, denser, Abies dominated forests. 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.

No use/trade is known.

Improved forest management practices to reduce the impact of high intensity fire would improve habitat quality for this species. Modern taxonomic work is needed on this species, in particular to investigate if it differs from Gastroboletus vividius. Historic sites should be revisited and appropriate habitat surveyed for this species.