CHOIROMYCES VENOSUS (Fr.) Th. Fr.
Svensk bot. Tidskr. 3: 240 (1909)
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Basionym:
Mylitta venosa Fr., in Lindblad, Bidrag. till Bleckings Flora: 248 (1830) et Summa veget. Scand.: 436 (1849)
Synonyms:
Choiromyces meandriformis Vittad., Monogr. Tuberac. (Milano): 51 (1831)
Choiromyces gangliiformis Vittad., Monogr. Tuberac. (Milano): 51 (1831)
Tuber album Sowerby, Col. fig. Engl. Fung. Mushr. (London) 3: pl. 310 (1800), sensu Tulasne et C. Tulasne (1851) non T. album Bull., Herb.France pl. 404 (1789)
Rhizopogon meandriformis (Vittad.) Corda, Icon. fung. (Prague) 6: 68 (1840)
Macroscopic characters:
Ascomata: hypogeous or subhypogeous, subglobose, often irregular in form and lobed, tuberculate, 2–8(–12) cm in size, smooth, initially whitish, becoming yellowish-brown, with reddish spots at maturity.
Gleba: firm, solid, whitish at first, becoming cream or pale yellowish, marbled at maturity with sterile, whitish to greyish, meander-like veins (which is the origin of the name “meandriformis”) surrounding the fertile areas.
Odour: strong, distinctive, becoming unpleasant at maturity.
Taste: nutty, hazelnut-like.
Edibility:
The gastronomic value of Choiromyces venosus is regarded differently across Europe. Some authors advise against consuming it raw or when overripe. In Northern Europe it is eaten as a delicacy; however, it is considered toxic (a gastrointestinal irritant) in Southern Europe. In Spain it is listed in Annex D (species that may not be traded commercially) of Spanish Royal Decree 30/2009 of 16 January 2009, laying down the health conditions for the trade in mushrooms for human consumption.
Habitat:
Choiromyces venosus grows in acid soils with high rainfall, associated with deciduous and coniferous trees, preferring clayey soils. It has been recorded in Navarra (Spain) associated with Quercus robur and in Hungary under Picea abies. Specimens are often visible above ground, although many complete their development underground.
Notes:
Immature specimens of Choiromyces venosus can be confused with the prized Alba white truffle, Tuber magnatum, and are sometimes sold fraudulently.
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Microscopic characters:
Asci: clavate to saccate, short-stalked, 120–180(–200) × 50–70 µm, 8-spored, not stained in Melzer’s Reagent.
Ascospores: 17–20 µm excluding ornament, globose, yellow-brown at maturity, ornamented with tube-like, truncate or tapered spines, 3–5 µm high, 2–3 µm across at the base. Some spores are ornamented with hemispherical warts.
Peridium: pseudoparenchymatous, composed of broad cells and interwoven hyphae.
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