Tuber bituminatum

Species associated with broadleaf trees, preferring calcareous soils, with globose to subglobose ascomata 2 to 5 cm in diameter, dark brown to black, with the surface completely covered with pyramidal warts, a labyrinthine gleba with white veins on a greyish-brown background, an intense odor resembling tar or bitumen, and a slightly bitter taste.

Asci subglobose to clavate, hyaline, short-stalked (pedicellate), 70 to 90 µm long, 60 to 75 µm wide, and usually containing one to four ascospores inside.

Ascospores ovoid to ellipsoid, yellowish ochre under the microscope, with very prominent ridges 3 to 7 µm high, 30 to 40 µm long excluding ornamentation, 25 to 32 µm wide, and an ornamentation composed of coarse ridges that unite to form an irregular mesh.