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Species Information
Summary: Features include 1) a spherical to lobed fruitbody with a thick rind-like skin that is pimpled on the exterior and marbled in cross-section, the surface color yellow-brown to ocher brown, 2) a spore mass that is cottony to powdery, colored grayish to purplish when mature and often separated into chambers by whitish bands, and 3) large spores that are round with short spines and are produced on mostly 8-spored asci. Elaphomyces ''muricatus'' may be parasitized by Cordyceps. It is abundant among truffles in the Pacific Northwest [and common elsewhere in North America], but represents a species complex temporarily designated by a European name, none in the Pacific Northwest being identical with the Europeans species (Trappe(13)). The description is derived from Arora(1) for Elaphomyces muricatus group except where specified.
Elaphomyces muricatus has been reported from BC in Redhead(5), from WA by Jumpponen(1), from OR by Luoma(1), and from CA by Desjardin(6). It is found in the United Kingdom (Hawker(1)).
Outer Surface: 2-5cm across, spherical to ovoid or somewhat lobed, very firm; ocher brown or yellow-brown; exterior "covered with minute hard pointed warts that give it a pimpled appearance", but these often hidden by crust of soil and mycorrhizal rootlets that is easy to brush away; peridium [skin] rind-like, firm and thick (0.2-0.5cm), "marbled when sectioned (dark brown to purplish brown with whitish to vinaceous-tinged veins)"
Interior: at first hollow, soon stuffed with cottony tissue, eventually becoming powdery when spores mature; white at first, soon grayish to purplish (and often separated into chambers by whitish sterile bands), finally becoming blackish and uniformly powdery, (Arora), somewhat gooey when young, becoming a fine black powder (Trappe, M.(3))
Odor: not very distinctive, (Arora), metallic, unpleasant (Trappe, M.(3))
Microscopic: spores 18-30 x 18-30 microns, "round, warted or warted-spiny, dark brown to black under the microscope"; asci "round to pear-shaped or irregular, mostly 8-spored, not forming a palisade (hymenium) and disintegrating soon after the spores form (and before they completely mature)"
Habitat / Range
single to gregarious in soil or duff in woods, (Arora), associated with members of Pinaceae and Fagaceae (Trappe)
Similar Species
Elaphomyces granulatus has a peridium that is not marbled in cross-section. Elaphomyces reticulatus is described as "Inner peridium obscurely marbled (in section), pale brown with whitish to pink veins; cortex mainly with flat warts", spores 19-28 microns in diameter with spines 2-2.5 microns long, whereas Elaphomyces muricatus is described as "Inner peridium distinctly marbled, dark reddish brown with pale brown veins; cortex mainly with pointed warts" and spores are 18-40 microns in diameter with spines 1.5-2.5 microns long, (Hansen, L.(1)). Scleroderma species usually have a distinct base or point of attachment, lack the small hard warts, usually grow closer to the surface or above it, and differ microscopically.
