Truffle Genus: Elaphomyces

Elaphomyces mutabilis ascospore Scale = 10 µm Elaphomyces sp. ascospore Scale = 10 µm

Kingdom: Fungi Phylum: Ascomycota Order: Elaphomycetales Family: Elaphomycetaceae   Elaphomyces virgatosporus ascospore Scale = 10 µm

Spore Characters

Surface: Spines, reticulation, or spiraled ridges to nearly smooth, 0.5-4 µm tall; smooth in one rare species, E. leucosporus Vitt.
Shape and Size: Globose, 8-50 µm in diameter including ornamentation; some species produce spores of two size groups within a single sporocarp, e.g. 10-15 µm and 25-35 µm. The smaller spores are dark and apparently aborted.
Wall: Single, 0.5-4 µm thick.
Color in Water: Blue-gray to gray, olive, brown, or black; in the rare E. leucosporus, known only from southern Europe, hyaline to pale yellow.
Melzer's Reaction: Not distinctive.
Comments: Elaphomyces spores can be difficult to differentiate from the globose, reticulate spores of some species of Scleroderma, Ruhlandiella, or Tuber or the globose, spiny spores of certain species of Genabea or Hydnotrya. The asci that contain Elaphomyces spores disintegrate at early maturity, so spores found within intact asci in mammal stomach contents will not be those of Elaphomyces. Of the genera mentioned above, only Elaphomyces includes species with blue-gray, olive, or nearly black spores.

View photos of Elaphomyces spores

Sporocarp Characters

Shape and Size: Subglobose to globose, 5-40 mm broad.
Peridium: Brown to dark blue or black, smooth to ornamented with hard, rounded warts, pyramids, or cones, often tomentose and enhusked by proliferated variously colored mycelium and ectomycorrhizae of associated trees or shrubs, crisp-fleshy to leathery to carbonaceous, 2-5 mm thick; this is the part of the sporocarp eaten by small mammals, which often discard the powdery spore mass of the gleba (Trappe and Maser, 1977).
Gleba: Hollow in youth, soon stuffed with asci and cottony hyphae; at maturity, the hollow is filled with a yellow to brown, olive, brown-black, blue-black, or black spore powder.
Odor: Not distinctive to metallic or garlicky.

View photos of Elaphomyces sporocarps

Name Derivation

An early name from Greek, elapho- (deer) and -myces (fungus), the "deer fungus" in reference to deer digging up this fungus and feeding on it. The origin of the name may be the earliest scientific recognition of mycophagy by wild animals.

Distribution

Associated with ectomycorrhizal trees and shrubs throughout the Northern Hemisphere from sea level to timberline. Also, a number of undescribed taxa have been found in South America, Australia, and New Zealand.
Season: Throughout the year; some sporocarps require many months to mature.
Species known from North Temperate Forests: About sixty-five.

Keys and Descriptions

The only monograph of the genus is that by Dodge (1929), now substantially out of date, although a number of regional treatments have appeared since. New treatments for Australia, New Zealand, eastern U.S. are in preparation (Castellano, pers. comm.) Montecchi and Sarasini (2000) cover many but not all European taxa.