Truffle Genus: Octaviania

Octaviania asterosperma basidiospore

Kingdom: Fungi Phylum: Basidiomycota Order: Boletales Family: Strobilomycetaceae

Spore Characters

Surface: Large conic to blunt warts composed of agglutinated spines, 1-3.5 µm long.
Shape and Size: Longitudinally symmetric, globose to ellipsoid, 9-23 x 9-19 µm (excluding ornamentation); sterigmal attachment straight, often prominent.
Wall: 1-2 layered, 0.5-3 µm thick.
Color in Water: Yellow to pale yellow-brown, the ornamentation hyaline to brown.
Melzer's Reaction: Not distinctive.
Comments: Globose spores of Octaviania species ornamented with large, conic to blunt warts can be distinguished from those of Sclerogaster by their larger diameter, but are difficult to differentiate from spores of some hypogeous Scleroderma spp.

View photos of Octaviania spores

Sporocarp Characters

Shape and Size: Globose to irregular, 1-4 cm in diameter.
Peridium: White overall to mottled with brown or brown overall. Some species becoming red, blue, or black where bruised; rhizomorphs lacking or inconspicuous.
Gleba: White in youth, with age becoming yellow to brown, in some species reddening where cut; with small, empty chambers; columella lacking or rudimentary.
Odor: Not distinctive.

View photos of Octaviania sporocarps

Name Derivation

Named by German botanist Karl Ersnt Otto Kuntze (1843-1907) (1893) in honor of the Italian botanist, Vincento Octaviani. Species originally assigned to Octaviania later proved to include both ornamented and smooth-spored species. The smooth-spored Octaviania species have all been assigned to the genus Melanogaster. Octaviania and Melanogaster, as it happens, bear little resemblance to each other.

Distribution

Widely distributed in temperate zones of the Northern Hemisphere, but infrequent; associated with ectomycorrhizal conifers and hardwoods. Also in Australia and New Zealand.
Season: Mostly autumn, but occasionally spring or summer.
Species known from North Temperate Forests: Nine have been described, but most of these belong to other genera. Several additional, undescribed species have been found in western North America.

Keys and Descriptions

Singer and Smith (1960) cover all the species described to date; Pegler and Young (1979) describe and illustrate representative spores. Montecchi and Sarasini (2000).