Rhizopogon ellipsosporus is known from a single site in the Coast Range of California, and scattered sites in the SIskiyou Mountains and Cascade Range in Oregon, USA. Based on the few collections made, it appears to be restricted to mature and old growth forests, which are under threat from fires, logging and climate change.  It is listed as Imperiled (G2) by NatureServe (explorer.natureserve.org) with an estimate of only up to 20 element occurrences (locations).  This is an hypogeous species and thus has low detectability and its population size is likely larger than the few records indicate.  Conservatively it is estimated that there are up to 100 X more sites than are the currently known records, each with 4- 6 mature individuals, resulting in a conservative estimate of 3,20-4,800 mature individuals (8 sites x 100 x 4-6 individuals) distributed in small, scattered subpopulations. It is assessed as Vulnerable.

Described from a collection made ~15 miles west of Grants Pass, Oregon, USA (Trappe & Castellano 2000).

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

Rhizopogon ellipsosporus is a rare hypogeous fungus with a reddish brown to brown peridium with scattered appressed rhizomorphs, a pale yellow-brown gleba, and rather short and wide spores (for a Rhizopogon).

Known from a single site in the California Coast Range, and seven locations in Oregon; most of which come from old growth forests.

Known from a single site in the Coast Range of California, and scattered sites in the SIskiyou Mountains and Cascade Range in Oregon, USA.

Currently known from eight locations in northern California and Oregon. Based on the few collections made, it appears to be restricted to mature and old growth forests, which are under threat from fires, logging and climate change.  It is listed as Imperiled (G2) by NatureServe (explorer.natureserve.org) with an estimate of only up to 20 element occurrences (locations).  This is an hypogeous species and thus has low detectability and its population size is likely larger than the few records indicate.  Conservatively it is estimated that there are up to 100 X more sites than are currently known records, each with 4- 6 mature individuals resulting in a conservative estimate of 3,20-4,800 mature individuals (8 sites x 100 x 4-6 individuals) distributed in small, scattered subpopulations.

Hypogeous, solitary or scattered in duff or soil in old growth forests, Ectomycorrhizal, likely associated with Douglas-fir (Pseudotsuga menziesii). Fruiting in fall, more rarely in spring. This species is dependent on mycophagy (primarily eaten by small mammals) for spore dispersal, and is likely restricted to old growth forests.

This is a ectomycorrhizal fungus species dependent on living host trees for viability. The major threat to this species and its co-occurring co-generic taxa is habitat destruction,via the logging of old-growth forests to which it appears confined too and an increase in fire frequency and intensity. The extent of old growth forest in the Pacific Northwest of North America has declined 90% in the last century (Society of American Foresters 1984, Haynes 1986). Fire is big threat to this species’ populations. A stand replacing fire could severely degrade and/or diminish its current range.

Protection of mature and old growth forests in the Pacific Northwest is needed.  Logging and machine clearing of understory vegetation should be limited in mature and old growth forest in areas where this species might occur.

More data are needed on its population size and trends along with details on its habitat requirements and restraints.

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.

Haynes, T.W. 1986. Inventory and value of old-growth in the Douglas-fir region. PNW-RN 437. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR.

https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.57.10381/Rhizopogon_ellipsosporus

MyCoPortal. Mycology Collections Portal. Available at: http://mycoportal.org (queried December 2024)

Trappe, J.M. and Castellano, M.A. 2000. New sequestrate Ascomycota and Basidiomycota covered by the Northwest Forest Plan. Mycotaxon. 75: 153–179

Society of American Foresters. 1984. Scheduling the harvest of old growth : Old-growth forests in the Pacific Northwest : a position of the Society of American Foresters and Report of the SAF Task Force on Scheduling the Harvest of Old-Growth Timber. Bethesda, MD.

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