Suillellus luridus

In both coniferous and broadleaved forests on calcareous soils, with a convex to flattened cap, 6 to 18 cm in diameter, brownish-yellow to reddish-orange, with flesh turning blue on cutting, orange under the tubes, a stipe adorned with a reddish reticulum in the upper part, with a mild fungal odour and sweet taste.

Pileipellis composed of filamentous, heavily interwoven hyphae, 4 to 7 µm wide, with pale brown intracellular pigment, often with abundant surface encrustations, septate and with simple septa (clamps absent).

Cheilocystidia and pleurocystidia cylindrical to fusiform, 40 to 65 µm long, 5 to 10 µm wide, hyaline or with only faint yellowish pigment inside.

Basidia clavate, 40 to 50 µm long, 12 to 16 µm wide, with a simple base, 4-spored.

Spores ellipsoidal, smooth, thick-walled, yellowish-brown under the microscope, 10 to 12 µm long, 5 to 6 µm wide, with a minute eccentric apiculus at one end, and containing oil droplets of various sizes inside.