SPECIES FACT SHEET
Scientific Name: Rhizopogon inquinatus A.H. Smith
Division: Eumycota
Subdivision: Basidiomycotina
Class: Gasteromycetes
Order: Hymenogastrales
Family: Rhizopogonaceae
Conservation Rankings and Status:
Global: G2G3
State: OR S1S2, WA Not ranked
Oregon Biodiversity Information Center (ORBIC) List 2
(Ranks from ORBIC, http://orbic.pdx.edu accessed August 16, 2013)
Type Locality: Priest River Experimental Forest, Idaho
Type: A.H. Smith 68016
Originally described by Smith (1966) from Priest River Experimental Forest,
Idaho. There are no known synonyms.
Technical Description: Rhizopogon inquinatus is characterized by the fuscus
stains on the peridium and the large amyloid globules in the peridium.
Fruiting body about 2 cm diameter, globose to subglobose, surface dry and
appressed fibrillose when perfectly fresh, whitish at first, on exposure to air
pallid buff and where handled slowly staining inky-fuscous but with an
intervening reddish stage, KOH on white surface reddish then fuscous-black,
FeSO4 olivaceous but finally black, odor none. Gleba olive at maturity, when
cut soon becoming olive-brown to black but when dried brownish olivaceous,
rubbery in consistency, chambers labrynthiform. Columella absent. Spores
6.5-7.5 (-8) x 3-3.5 µm, elliptic to oval and with a distinct cup-like truncation
at base, smooth, walls only slightly thickened, dingy yellowish in KOH singly,
dull cinnamon in masses, in Melzer's reagent dull yellowish singly and dull
rusty brown in groups. Basidia 4- and 6- spored (possibly all 8- spored).
Basidioles hyaline, thin-walled, subgelatinous, 6-9 µm broad. Trama of
gelatinous narrow branched interwoven hyphae 3-5 µm diam; subhymenium of
gelatinous-filamentous branches extending to a weak cellular region below
hymenium. Peridium of loosely interwoven hyaline thin-walled filaments 3-5
µm, diameter smooth and the layer clean (as seen in KOH fresh), as revived in
KOH with dark cinnamon granules of amorphous pigment, in Melzer's reagent
(both fresh and dried) with dark violet globules up to 30 µm or more diameter
free in the layer, no sphaerocysts or large inflated cells present. Clamp
connections none. All tissues nonamyloid.
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Rhizopogon is one of several genera included among the “false truffles.” There
are perhaps four groups of fleshy fungi with which species of Rhizopogon are
likely to be confused: 1) puffballs, 2) gastroid agarics, 3) other “false truffle”
genera, and 4) true truffles. False truffles, puffballs, and gastroid agarics are
included within the Gasteromycetes – basidium-producing fungi whose spores
are produced internally and not forcibly discharged from the basidia. The spore
mass of puffballs (Lycoperdon and allies) is usually white, firm, and without
readily discernable chambers when young, and becoming powdery and rather
quickly dispersed at maturity. The fruiting bodies of puffballs are usually found
aboveground. While the presence of a cap and stalk is clearly evident in some
gastroid agarics, species of Endoptychum, Brauniellula or Thaxterogaster may
bear a stronger resemblance to false truffles. However, dissection of a gastroid
agaric will reveal at least some evidence of a percurrent stalk (one that extends
through the spore mass to the top of the cap). At maturity, the sporocarps of
gastroid agarics are usually found partially or fully aboveground. Among other
genera of false truffles (e.g., Alpova, Gautieria, Hydnangium, Hymenogaster,
Hysterangium, Leucophleps, Martellia and Truncocolumella), Rhizopogon
generally is distinct in exhibiting the following set of features: 1) an exterior
surface often overlain with soft mycelial strands (rhizomorphs), 2) spore mass
composed of minute, generally non-gelatinous chambers (best seen with hand
lens), 3) stalk (basal and within spore mass) typically lacking and 4) spore
surfaces smooth. Microscopically, true truffles are readily differentiated from
species of Rhizopogon by the presence of sexually produced spores borne within
asci. Macroscopically, however, fruiting bodies of true truffles will, as is
typically true of Rhizopogon, show no evidence of a stalk, either basal, or within
the spore mass. The interior of a true truffle, however, will typically differ from
that of Rhizopogon species in being either 1) solid and marbled with veins, or 2)
completely hollow or with quite evident folds and chambers. Because of the
need to recognize multiple, subtle, microscopic anatomical features and use
chemical staining procedures, it is probably unrealistic to expect a lay
mycologist to do more than recognize that a fleshy fungus specimen is likely to
be included in the genus Rhizopogon. Identification to species will almost
certainly require the services of a Rhizopogon "expert".
Life History: Fruits in September and October. This species is probably
ectomycorrhizal with Pinaceae and depends on mycophagy (consumption by
animals) for spore dispersal.
Range, Distribution, and Abundance: Known from 3 sites in the Northwest
Forest Plan area, located in the Oregon Western Cascades Physiographic
Province on the Willamette National Forest. There were no detections of this
species during Random Grid CVS/FIA plot surveys. Also known from Idaho.
FS/BLM lands where documented: Willamette National Forest.
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Habitat Associations: Two sites were documented in the mountain hemlock
series/wet mountain hemlock habitat association and one site was
documented in the western hemlock series/western hemlock wetlands
association. Elevation of the sites ranges from 454 m. (1,490 feet) to 1,374 m.
(4,507 feet) with a mean of 1,057 m. (3,467 feet).
Threats: With the assumption that this species is ectomycorrhizal, it is
reasonable to assume that as with ectomycorrhizal fungi in general, threats to
the species are activities or events that result in direct or indirect impacts to
fungal individuals or mycelial mats. These threats include activities that:
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remove or destroy the fungal organism
intensively or extensively remove or consume the woody substrate, forest
floor litter, or tree or shrub hosts with which the species is associated
remove trees or other vegetation that significantly modifies the
microclimate at the species’ site
compact soil or change soil chemistry
Impacts to fungal organisms can reduce both the biomass and species diversity
within a community of ectomycorrhizal fungi. Attendant reductions in
production of false truffles may, in turn, potentially reduce dispersal of their
spores by small mammals. Fire is not a potential threat to Rhizopogon
iniquinatus because the general habitat where it occurs is cool and wet and not
prone to fires. However, if fire were to occur, particularly a hot ground fire, it
could harm populations from disturbance to soil or by damaging host trees.
Climate change may result in a decline of vigor and may result in extirpation of
this species. An increase in temperature or a decrease in precipitation could
affect disjunct populations.
Conservation Considerations: Revisit documented sites to reconfirm
presence and better define habitat. Conduct surveys to locate new populations
on federal land. Buffer known sites and protect from wildfire; prescribed burns;
vegetation management projects that would remove potential host plants,
disturb soil or duff, or change habitat or microclimate conditions; and grounddisturbing activities (e.g., recreational vehicles, road building, grazing) that
would reduce moisture-retaining ground covers. Consider vegetation
management activities within known site buffers that are likely to maintain or
improve ectomycorrhizal fungal habitat quality (e.g. moderate hand-thinning of
an overstocked stand or augmenting a deficient volume of coarse woody
debris). When conducting vegetation management activities in areas with good
habitat potential, consider leaving scattered and clumped host trees and ample
coarse woody debris while minimizing soil compaction and burn severity of
activity-related fires.
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As a mycorrhizal species, Rhizopogon inquinatus forms symbiotic associations
with the fine root systems of plants, growing out into the soil matrix. To provide
a reasonable assurance of the continued persistence of occupied sites consider
incorporation of patch retention areas (as described in Standards and
Guidelines 1994, C-41) with occupied sites wherever possible.
Other pertinent information (includes references to Survey Protocols,
etc): The survey protocol for fungi is located on the ISSSSP website:
http://www.fs.fed.us/r6/sfpnw/issssp/documents/inventories/inv-sp-fuver1-2008-12.pdf.
The survey protocol for Survey and Manage fungi is located on the Survey and
Manage website: http://www.blm.gov/or/plans/surveyandmanage/protocols/
Prepared by: Marcia Wineteer, Medford BLM
Date: April 2013
Edited by: Rob Huff, BLM/FS Portland, Oregon
Date: February 2014
ATTACHMENTS:
(1)
References
(2)
Map of Species Distribution
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ATTACHMENT 1:
References
Arora, David. 1979. Mushrooms Demystified – A Comprehensive Guide to the
Fleshy Fungi. Ten Speed Press, Berekeley, California. 959 pp.
Castellano, Michael A. and Thomas O’Dell. 1997. Management
Recommendations for Survey and Manage Fungi. Version 2.0.
Castellano, Michael A., Jane E. Smith, Thom O’Dell, Efren Cazares, and Susan
Nugent. 1999.Handbook to Strategy 1 Fungal Species in the Northwest Forest
Plan. General Technical Report PNW-GTR-572.
Cushman, Kathleen and Rob Huff. 2007. Conservation Assessment for Fungi
Included in Forest Service Regions 5 and 6 Sensitive and BLM California,
Oregon and Washington Special Status Species Programs. R6 USFS and
OR/WA BLM Interagency Special Status/Sensitive Species Program (ISSSSP).
http://www.fs.fed.us/r6/sfpnw/issssp/planning-tools/
Dewey, Rick and Jennifer Ferriel. 2007. Habitat Summary for Sensitive Fungi
Species.
http://www.fs.fed.us/r6/sfpnw/issssp/species-index/flora-fungi.shtml
Ferriel, Jenifer and Katie Grenier. 2008. Annotated Bibliography of Information
Potentially Pertaining to Management of Rare Fungi on the Special Status
Species List for California, Oregon and Washington. R6USFS and OR/WA BLM
Interagency Special Status/Sensitive Species Program (ISSSSP).
http://www.fs.fed.us/r6/sfpnw/issssp/planning-tools/
Oregon Biodiversity Information Center. 2010. Rare, threatened and
endangered species of Oregon. Oregon Biodiversity Information Center,
Institute for Natural Resources, Oregon State University, Portland, Oregon.
105pp.
http://orbic.pdx.edu/documents/2010-rte-book.pdf
Smith, Alexander H. and S.M. Zeller. 1966. A Preliminary Account of the North
American Species of Rhizopogon in Memoirs of The New York Botanical
Garden, Vol. 14, No. 2, March 15, 1966.
Trappe, James M., Randy Molina, Daniel L. Luoma, Efren Cazares, David Pilz,
Jane E. Smith, Michael A. Castellano, Steven L. Miller, and Matthew J. Trappe.
Diversity, Ecology, and Conservation of Truffle Fungi in Forests of the Pacific
Northwest. 2009. PNW-GTR-772. 202 pages.
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ATTACHMENT 2:
Map of Species Distribution
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