Halling, R.E.; Mueller, G.M. 2003. Leccinum (Boletaceae) in Costa Rica. Mycologia 95: 488-499.

Leccinum eximium (Pk.) Singer, Persoonia 7:319. 1973. Figs. 3, 15-17.
Boletus robustus Frost non Fr., Bull Buffalo Soc Nat Sci 2:104. 1874.
Boletus eximius Pk., J Mycol 3:54. 1887.
Ceriomyces eximius (Pk.) Murrill, Mycologia 1:148. 1909.
Tylopilus eximius (Pk.) Singer, Amer Midl Nat 37:109. 1947.

Pileus 3.5-8 cm broad, at first convex to plano-convex, with age plano-convex, dry to moist; disk even, at first violet brown (11E4), then chocolate brown (6F4); margin even, concolorous with disk; surface matted subtomentose to subvelutinous, becoming subtomentose to tomentose; sterile appendiculate flaps absent. Flesh 10-20 mm thick, white with a grayish lilac tint to white with pale violet brown tint or pale lilac brown, staining absent; odor mild; taste mild. Hymenophore tubulose, adnexed to depressed. Tubes 5-10 mm long, rarely grayish yellow (4B3) to light brown or brownish purple, becoming grayish brown to dark brown (9F8) to purplish brown (11F8), unchanging when injured; pores 3 per mm, dark brown or purplish brown, then dark pinkish brown, brown when bruised. Stipe (4-)6-15 cm long, 6-12(-20) mm wide, equal to subequal, strict or curved, not radicating, dry; upper half when young finely scabrous, very pale violet, with age subpruinose to scabrous, very pale violet; lower half when young finely scabrous to scabrous, very pale violet, with age scabrous to finely scabrous or subscabrous ridged, very pale violet to lilac or dull lilac gray (16D3); scabers brown; base white, staining not present. Stipe interior solid; flesh above when young pale violet brown to lilac brown, with age pale lilac brown to grayish lilac, staining not present; flesh at base grayish lilac to pale violet brown to pale lilac brown, staining not present. Basal mycelium white.

Basidiospores vinaceous brown to pinkish brown, 10.5-13.3 µm x 4.2-4.9 µm, Q = 2.55, smooth, ellipsoid to subfusoid to fusoid, inamyloid, with KOH pale brownish yellow. Basidia 21-34 µm x 8.5-11 µm, clavate, hyaline, 4-sterigmate. Hymenial cystidia 20-35 µm x 6-8 µm, rare, thin-walled, hyaline to golden-colored contents, narrowly fusoid. Tube trama boletoid, hyaline, lateral strata elements 3.5-8.4 µm wide, with age subgelatinous. Pileipellis hyphae a trichodermium, in KOH yellow ochraceous, inamyloid; elements 3.5-6 µm wide, elongated to cylindric or obtuse, encrusted with pigment (but dissolving in KOH), thin-walled, not gelatinized. Pileus trama interwoven, hyaline, inamyloid, thin-walled. Stipitipellis hyphae vertically oriented, parallel, giving rise to clusters of caulocystidia, 20-30 µm x 5-14 µm wide, cylindric to clavate to subfusoid, hyaline to brown contents, with encrusting pigment present (with purple acerose crystals dissolving in KOH). Stipe trama hyphae parallel, cylindric, hyaline, inamyloid. Clamp connections absent.

Habit, habitat and distribution: solitary to gregarious on soil under Quercus copeyensis, Q. seemannii, Q. rapurahuensis in Costa Rica.