Assessment Notes

Justification

Gastroboletus dinoffii is recognized by the top-shaped to highly irregular fruitbody, a thin, concealing peridium with a dull grayish brown upper portion, and deep red on lower parts, an olive tubular gleba, and an indistinct stipe, with a pad-like columella extending into the gleba. It is one of two Gastroboletus species known from California with amyloid trama, but it has inamyloid spores. It is apparently quite rare, being known from four localities and the identity of three of these requires confirmation. Because of this, there is a high degree of uncertainty surrounding the status of this species, and so it is assessed as Data Deficient.

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Taxonomic notes

This species was described from a collection made in San Bernardino National Forest in southern California, USA (Nouhra and Castellano 1995). This remains a poorly known species, and more collections and modern taxonomic work are needed. 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.

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Geographic range

Currently, this species has been reported from four locations; the type locality in southern California in the San Bernardino Mountains; two from northern California in the Mount Shasta area, and a single site in Klamath Co., Oregon, USA. However, these northern collections should be re-examined.

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Population and Trends

It is only known from four locations and four collections, and there are also some questions about whether the three northern collections represent the same species. More collections, and knowledge of suitable habitat are needed for a clearer assessment.

Population Trend: unknown

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Habitat and Ecology

This species is completely buried to emergent in duff under conifers. It is ectomycorrhizal, likely associated with three-needle pines or with fir. The type was found under Jeffrey Pine (Pinus jeffreyi), with White Fir (Abies concolor) in the area. The Mount Shasta and Oregon collections were from Ponderosa Pine (Pinus ponderosus) and White Fir forest. Fruiting is in summer and fall. This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal (Siegel et al. 2019).

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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 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.

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Conservation Actions

No specific conservation actions have been identified with regards to this species at this time. Modern taxonomic work is needed on this species. Historic sites should be revisited and appropriate habitat surveyed for this species.

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Use and Trade

No use/trade is known.

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Source and Citation

Siegel, N. 2021. Gastroboletus dinoffii. The IUCN Red List of Threatened Species 2021: e.T198479606A198488785. https://dx.doi.org/10.2305/IUCN.UK.2021-2.RLTS.T198479606A198488785.en .Downloaded on 25 September 2021

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• Country occurrence