Truffle Genus: Acaulospora

Kingdom: Fungi Phylum: Zygomycota Order:Glomales Family:Acaulosporaceae

Spore Characters

Surface: Roughened.
Shape and Size: Ellipsoid, broadly fusiform, subglobose to globosee, (140-) 160-200 (-240) x (125-) 150-175 (-200) µm diam.
Wall: 2-layered; outer wall 2.5-5 µm thick, inner wall 7-15 µm thick.
Color in Water: Dark brown to black.
Melzer's Reaction: Distinctive, inner wall amyloid.
Comments:

View photos of Acaulospora spores

Sporocarp Characters

Shape and Size: Irregular, dark brown, up to 2.5 x 1.5 x 1.5 cm.
Peridium: Absent, spores apparent on surface.
Gleba: Dark brown with black dots which are the spores.
Odor: Not distinctive.
Comments: Sporocarps appear as "lumps of dirt" to untrained eye.

View photos of Acaulospora sporocarps

Name Derivation

 Named by Trappe and J.W. Gerdemann (1974) in reference to the sessile (acualo = without stem) spores.
Acaulospora sporocarpia named by Berch (1985) in reference to the spores forming sporocarps which is an unusual feature in the genus Acaulospora.

Distribution
Hypogeous in woodlands in New Mexico and Arizona.

Season: August and September.

Species known from North Temperate Forests: The genus contains many species but only A. sporocarpia forms a truffle-like sporocarp.

Keys and Descriptions
Berch (1985).

References
Berch, S.M. (1985). Acaulospora sporocarpia, a new sporocarpic species, and emendation of the genus Acaulospora (Endogonaceae, Zygomycotina.). Mycotaxon 23: 409-418.