Choiromyces olbiensis Tul. & C. Tul. Giorn. Bot. Ital. anno I, parte 1, Vol. II: 60 (1845) 
Ascomata: hypogeous to partially emergent at maturity, 2–5 cm in size, subglobose, short base, cream colour at first, becoming brown, black spots on the sun-exposed parts or when manipulated, smooth
Peridium: 300–500 µm thick, whitish in cross section, pseudoparenchymatous, composed of subglobose cells, 20–50 µm diam, thin-walled, hyalines, yellowish and angular to oblong in the outermost layers.
Gleba: solid, fleshy, succulent, whitish with small pale grey pockets at first, maturing to greenish gray pockets of fertile tissue separated by whitish, sometimes with salmon pink spots, sterile veins. Often with small holes indicating mycophagous activity
Odour: faint, distinctive.
Terfezia olbiensis grows in calcareous, clayey, alkaline soils, associated with Pinus spp. and Quercus ilex, with no presence of Cistaceae, from mid-March to mid-April.
Terfezia olbiensis has been considered as an immature form of Terfezia leptoderma and treated as synonyms by several authors. Molecular analysis have shown several distinct clades within spiny spored Terfezia species with pseudoparenchymatous peridium. Terfezia olbiensis differs from other spiny spored Terfezia species by its habitat, growing in basic soils associated with trees and not with Cistaceae plants and by having the smaller spores, average spore size 16–18 µm including ornament, with the shorter spines, 1–2 µm long.
Asci: nonamyloid, ellipsoid to ovate, citriform, sessile or short-stipitate, 60–90 x 50–60 µm, walls 1–2 µm thick, with 6–8 irregularly disposed spores, randomly arranged in fertile pockets.
Ascospores: globose, (15–)16–18(–19) µm diam (median = 17 µm) including ornament, 13–15(–16) µm (median = 14 µm) without ornament, hyaline, smooth and uniguttulate at first, by maturity yellow ocher and ornamented with conical spines, pointed, straight, separate, 1–2(–2,5) µm long, 1 µm wide at the base