SPECIES FACT SHEET
Scientific Name: Choiromyces venosus (Fr.) Th. Fr. 1909
Order: Pezizales
Family: Terfeziaceae
Conservation Status:
Global: G4G5
State: OR S1, WA Not ranked
Oregon Biodiversity Information Center (ORBIC) List 2
(Ranks from ORBIC, http://orbic.pdx.edu accessed August 16, 2013)
Type Locality: Sweden. Described by Fries (1830) as Mylitta venosa Th. Fries
and in 1909 transferred it to Choiromyces venosus. Known synonyms include
C. meandriformis Vittadini (1831).
Technical Description: Sporocarp is irregularly folded-lobed, up to 10 cm
broad, almost smooth, slightly fibrillose, pink-buff to fawn. Gleba solid with
gray-buff, later brown. Odor faint, stronger when decaying; Spores globose, 2230 microns broad including spine and rods, pale brown at maturity.
Choiromyces is found on one side of the true truffle family (Terfeziaceae) and
Tuber, the fabled edible fungi are the other (Tuberaceae). Choiromyces looks
like the edible truffles in the Tuber genus but it is harder and their exterior is
rougher and more copiously lobed. This truffle is distinguished by its unique
spore ornamentation of spines and rods that are up to 6 microns high and 1
micron wide.
Life History: This taxon is hypogeous (grows underground) and a presumed
ectomycorrhizal former. Sporocarps are formed below the soil surface and are
associated with western hemlock and Douglas fir roots. Fruits in October. It
depends on mycophagy (consumption by animals) for spore dispersal.
Range, Distribution, and Abundance: Known from Europe and both North
American coasts. In North America, this is a very rare species with only three
known populations, two in the Pacific Northwest. Oregon: Lane Co. on
Eugene BLM’s Mohawk Research Natural Area (site is in GeoBob) California:
Humboldt Co. at King Range National Conservation area.
FS/BLM lands in Oregon and Washington: Documented on Eugene BLM.
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Habitat Associations: The Oregon population is located in the western
hemlock plant association, in TSHE wetlands habitat type. It is located at 1677
feet in elevation.
Threats: Because the species is associated with the roots of host trees, any
adverse impact to those hosts or actions that would disturb the soil and duff in
the vicinity of fruiting bodies could have an adverse effect on the species. Fire
could be a potentially harmful to C. venosus due to high frequency in the lower
elevation habitats having a potential to kill host trees.
Conservation Considerations: Buffer known populations from management
activities that include tree removal and soil compaction or disturbance.
Consider buffering populations from prescribed burns.
Other pertinent information (includes references to Survey Protocols,
etc): The survey protocol for sensitive 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: Jenny Lippert, Willamette NF
Date: March, 2013
Edited by: Rob Huff, BLM/FS Portland, Oregon
Date: January, 2014
ATTACHMENTS:
(1)
References
(2)
Map of Species Distribution
(3)
Photographs of Species
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ATTACHMENT 1: References
Arora, D. 1975. Mushrooms Demystified. Ten Speed Press, Berkeley, pp. 854855.
Castellano, M.A., J.E. Smith, T. O’Dell, E Cazares and S. Nugent. 1999.
Handbook to the Strategy 1 Fungal Species in the Northwest Forest Plan, GTR476. USDA Forest Service, PNW Research Station, Corvallis.
Castellano, M.A and T. O’Dell. 1997. Management Recommendations for survey
and manage fungi. Version 2.0. Group 4: 1-16.
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ATTACHMENT 2: Map of Species Distribution in OR/WA
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ATTACHMENT 3: PHOTOS
Photos of Choiromyces venosus:
Photo courtesy of E Dannell, from Castellano et al, 1999.
The best photos are from the Trufamania website:
http://www.trufamania.com/Choiromyces%20venosus%20English.htm but
are copy righted. Photos show the truffle with fawn-colored internal matrix and
distinctive spiny spores.
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