Boletus amyloideus is a rare species of bolete fungus in the family Boletaceae. It was described as new to science in 1975 by mycologist Harry D. Thiers, from collections made in California. It fruit bodies have a convex to somewhat flattened reddish-brown cap measuring in diameter. The pore surface on the cap underside is bright yellow, with small angular pores and tubes measuring 4âÂÂ8 mm long. The spore print is olive-brown; basidiospores are smooth, amyloid, spindle shaped to ellipsoid, and have dimensions of 13âÂÂ16 by 4.5âÂÂ5.5 üm. The bolete is known only from coastal California, where it grows on the ground in mixed forests. Its edibility is unknown.