Truffle Genus: Hydnobolites

Hydnobolites cerebriformis ascospore scale = 10 µm Hydnobolites californicus ascospore

Kingdom: Fungi Phylum: Ascomycota Order: Pezizales Family: Tuberaceae

Spore Characters

Surface: With a broad-meshed, honeycomb-like reticulum, 3-4 µm tall.
Shape and Size: Globose, 12-24 (-30) µm in diameter excluding ornamentation.
Wall: Single, 0.5-1 µm thick.
Color in Water: Hyaline to pale brown.
Melzer's Reaction: Not distinctive.
Comments: Hydnobolites spp. are difficult to separate from Terfezia spinosa Harkn., T. longii Gilkey, and T. terfezioides (Mattirolo) Trappe on the basis of spores alone. Its pale colored spores readily distinguish it from other genera with globose, reticulate spores because similar spores of those genera (Elaphomyces and Scleroderma, Hydnotryopsis and related genera, and Tuber) are darkly pigmented.

View photos of Hydnobolites spores

Sporocarp Characters

Shape and Size: Subglobose to irregular, furrowed, 0.3-3 cm in diameter.
Peridium: White to brown, glabrous to scabrous.
Gleba: Gray to solid brown, marbled with white veins.
Odor: Mild to pungent.

View photos of Hydnobolites sporocarps

Name Derivation

Named by French botanist and mycologist Louis René Tulasne (1815-1885) and his younger brother French physician and mycologist Charles Tulasne (1816-1884) (1843) from Greek hydno (fungus), -bol- (a lump) and -ites (having the nature of), hence " a fungus having the nature of a lump."

Distribution

North America and Europe. This genus is infrequently encountered and is usually localized.
Season: Summer and autumn.
Species known from North Temperate Forests: Two.

Keys and Descriptions

Gilkey (1939, 1954) described H. californicus Fischer, known only from California and Oregon, and Hawker (1954) described H. cerebriformis Tul. and Tul., which occurs in Europe and eastern North America.