Described from a Type collection made near Mount Hood, Oregon, USA (Smith & Zeller, 1966). 

Many Rhizopogon lack distinctive morphological characters, and can only be reliably identified with genetic sequences.

Rhizopogon brunneiniger is a hypogeous fungus with a rounded to irregular fruitbody with a rubbery texture, a smooth, shiny, dark cinnamon to dark red-brown peridium, which develops blackish brown stains when handled, and a whitish to olivaceous gleba.

Currently known from 11 mostly disjunct locations in California and Oregon, USA.

Currently known from three highly disjunct locations in California; one coastal north of San Francisco, one in the southern Sierra Nevada mountains, and one in the Siskiyou range, and from eight sites in the Coast and Cascade Range in Oregon, USA.

Currently known from 11 locations in Oregon and California, USA, over a widespread area. Little data to assess trends, or associating this species to a habitat type is available.

Typically hypogeous, more rarely erupting from duff. Ectomycorrhizal, probably associated with multiple members of Pinaceae. Most sites have Hemlock (Tsuga spp.) present, others have Pine (Pinus spp.), fir (Abies spp.), and Douglas-fir (Pseudotsuga menziesii). Fruiting in fall, more rarely spring and summer. This species is dependent on mycophagy (primarily eaten by small mammals) for spore dispersal. Many Rhizopogon species have spores which stay viable in soil for many years; waiting for conditions to be optimal before growing. It is unknown if Rhizopogon brunneiniger is one of the ‘sporebank’ species. 

Prolonged droughts and decades of fire suppression have drastically altered western montane 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.

This species is included on the United States Forest Service Northwest Forest Plan Survey and Manage list of rare/old growth forests dependent fungi (Castellano et al. 1999).

Modern taxonomic work on Rhizopogon. Habitat associations of this species. Extent of populations.

None known.

Castellano, M., Smith, J.E., O’Dell, T., Cázares, E. and Nugent, S. 1999. Handbook to Strategy 1 Fungal Species in the Northwest Forest Plan. General Technical Report PNW-GTR-476. United States Department of Agriculture.

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

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.

Smith, A.H. and Zeller, S.M. 1966. A preliminary account of the North American species of Rhizopogon. Memoirs of the New York Botanical Garden. 14: 1–178