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

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. Apparently quite rare; described from the San Bernardino mountains under Jeffrey Pine, known from two sites at Mount Shasta and a single site in Klamath Co., Oregon.

Currently reported from four locations; the Type location 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 reexamined.

Only known from four locations and four collections; there is also some question if the three northern collections represent the same species. More collections, and knowledge of suitable habitat are needed for a proper assessment.

Completely buried to emergent in duff under conifers. 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 in summer and fall. This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal (Siegel et al. 2019).

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.

No specific conservation actions has 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.

None known.

MyCoPortal. 2020. Mycology Collections Portal. Available at: http://mycoportal.org

Nouhra, E. and Castellano, M.A. 1995. NATS truffle and truffle-like fungi 3: Gastroboletus Dinoffii sp. nov. Mycotaxon. 55:179-183

Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. and Ikeda, D. 2019. A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.