TUBER OLIGOSPERMUM (Tul. & C. Tul.) Trappe
Mycotaxon 9(1): 336 (1979)
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Basionym:
Terfezia oligosperma Tulasne et C. Tulasne, Fungi Hypogaei 176, Tab. XXI, fig. XV (1851)
Synonyms:
Delastreopsis oligosperma (Tul et C. Tul.) Mattirolo (1904-05), Boletim da Sociedade Broteriana 21: 95
Lespiaultinia oligosperma (Tul et C. Tul.) Gilkey (1954), North American Flora Series II, part 1: 25
Macroscopic characters:
Ascomata: hypogeous, subglobose or irregular in shape, gibbous, lobed, 2–3 (–5) cm across, smooth, pubescent at first, glabrous at maturity; initially whitish, becoming light ochre, brown at maturity, sometimes with reddish patches.
Gleba: firm, solid; whitish at first, then light brown, darker at maturity, marbled with numerous whitish, branching veins.
Odour: faint and pleasant when young, nutty, similar to that of other immature truffles; strong, garlicky, acetylenic and unpleasant at maturity. Detectable by truffle dogs.
Taste: strong, garlicky at maturity.
Habitat
Described in the literature from sandy soils under pines and holm oaks, with a highly variable ripening period from autumn to spring. Found in Albacete in clay and limestone soils, under pines, inhibiting plant growth and producing "burns"; ripening here in May and June.
Notes:
Tuber oligospermum was originally described as Terfezia by the Tulasne brothers on account of its spherical spores. As the asci are 2–4-spored and Terfezia are usually 8-spored, it was named Terfezia oligosperma (few spores). Although spherical spores are not very common in the genus Tuber, the gleba and spore ornamentation of this species are more consistent with Tuber than with Terfezia, and it was consequently transferred to Tuber oligospermum by Trappe in 1979.
Edible when young. Very common in Morocco, which exports large quantities to Europe for the truffle canning industry owing to its resemblance to Tuber magnatum.
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Microscopic characters:
Asci: subglobose to ovate, thick-walled (1–2 µm thick), short-stalked, 70–100 (–130) × 60–80 (–90) µm excluding stalk, 1–4 (–5)-spored (usually 2–3-spored or 3–4-spored depending on collection).
Ascospores: 25–46 × 25–40 µm excluding ornament, size variable depending on the number of spores per ascus, Q range = 1.00–1.15, globose to broadly ellipsoid, yellow, translucent, ornamented with a regular reticulum with polygonal meshes 4–5 (–8) µm high, 4–7 across the width of the spore.
Peridium: 150–250 µm thick, composed of agglutinated, interwoven, hyaline hyphae, covered with hairs in young specimens. Hairs 50–150 µm long, thick-walled, tapered, hyaline, septate.
Notes: Although spores are described in the literature as globose, ellipsoid spores are quite common.
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