"Diagnosis — A medium-sized to large Tricholoma, with a distinct ring, and fawn to dark brick, confluent fibrillose patches on the pileus and girdles on the stipe. Mycorrhizal with Pinus and possibly Picea.
Pileus 40–100 mm, at first hemispherical to convex with involute, margin, later convex to flattened, often with low, broad umbo, in central part soon breaking up into appressed, ± confluent scales, which are fawn, orange brown to dark brick, on a cream to straw yellow background; scales gradually or more abruptly thinning out towards the marginal zone, which is typically white to straw yellow or pale mouse grey; margin in young fruit bodies shaggy due to remnants of veil, but soon ± smooth to somewhat felty-costate. Lamellae emarginate, with even to somewhat eroded edges, whitish, with age sometimes with orange brown spots, rather close to medium spaced. Stipe 50–100 × 15–25mm, cylindrical or tapering downwards, often somewhat rooting, with a distinct, persistent, cuff-like, cottony-woolly ring, whitish
and granulose or slightly fibrillose above ring, below ring with irregular, fawn, orange brown to dark brick confluent girdles and patches on a whitish background, basal part occasionally with a weak greenish tinge. Flesh whitish; smell sweetish, perfumed fruity, similar to Inocybe corydalina or Hemipholiota heteroclita; taste unknown. Spores 4.5–6.7 × 3.9–5.5 μm, average 5.1–6.0 × 4.4–4.9 μm, predominantly broadly ellipsoid, Q = 1.0–1.5,average 1.15–1.31. Basidia 30–40 × 6–8 μm, 4-spored.
Cheilocystidia not observed. Pileipellis cutis made up of cylindrical, warm brown hyphae, 50–300 × 5–15(–20) μm, pigment not incrusting. Clamp connections absent.
Ecology & Habitat — Ectomycorrhizal with Pinus and possibly Picea, mainly in forests on calcareous ground.
Known distribution — Central Sweden (holotype), Norway, Spain and Turkey; most likely widespread in Europe.
Notes — According to the phylogenetic analysis the new species is close to T. dulciolens. Both species share small spores, but T. ilkkae is easily distinguished from T. dulciolens by the shorter stem and much darker pileus scales and stipe girdles.
Another similar species is T. caligatum, which is distinguished by larger spores and by slightly darker, more contrasting pileus scales and stipe girdles. In addition, the two species differ in habitat and distribution, as T. caligatum seems to be a strictly Mediterranean species, in contrast to T. ilkkae, which so far is known from more temperate environments. Finally, T. matsutake differs by duller colours, larger fruit bodies and larger spores.
