Described from a single collection made near Mineral, in Tehama County, California, USA (Thiers 1979).
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, while for others, such as G. citrinobrunneus, the closest relatives are not known yet (Siegel et al. 2019).
Gastroboletus citrinobrunneus is a rare and poorly known species, recognized by the irregularly convex, bright yellow and brown cap, yellow pores and dark blue staining on all parts. Known from five collections, from three locations in the northern Sierra Nevada and southern Cascade Range of California, USA, in mid- to high-elevation Abies forests.
Modern taxonomic work, and targeted surveys for this species is needed before a proper assessment can be made. Therefore I recommend listing it as Data Deficient (DD).
Mid- to high-elevation forests in the Norther Sierra Nevada and Southern Cascade Mountains in California, USA.
Very rare, only known from three locations, and five collections. More collections, a better understanding of this species, and knowledge of suitable habitat are needed to properly assess population and trends of this species.
Population Trend: Uncertain
Occurring in mid- to high-elevation fir (Abies) forests. Fruit bodies are completely buried to partially exposed in duff or soil. Ectomycorrhizal, likely associated with White Fir (Abies concolor) and Red Fir (Abies magnifica), and possibly other members of Pinaceae. Fruiting in summer. This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal.
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.
Protect known sites from management activities, including logging, fuels reduction, or other development and disturbance. Add to USFS sensitive species list.
Modern taxonomic work is needed on this species; how does it differ from Gastroboletus turbinatus var. flammeus?
Historic sites should be revisited and appropriate habitat surveyed for this species.
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.
Thiers, H.D. 1975. California Mushrooms – A Field Guide to the Boletes. Hafner Press.
Thiers, H.D. 1979. New and interesting hypogeous and secotioid fungi from California. Beihefte zur Sydowia 8:381–390.
Thiers, H.D. and Trappe, J.M. 1969. Studies in the genus Gastroboletus. Brittonia. 21(3):244-254