About Boletus fibrillosus Thiers
Boletus fibrillosus, commonly called the fib king, is a basidiomycete fungus in the genus Boletus. Its holotype was collected in Mendocino County, California. Phylogenetic analysis places it in a closely related clade alongside B. pinophilus, B. regineus, B. rex-veris, B. subcaerulescens, and Gastroboletus subalpinus.
Its cap can reach up to 17 centimetres (6+1⁄2 inches) wide, and ranges in color from buff to brown to dark brown, with a texture that is wrinkled to finely fibrous. It has yellow tubes, and white to buff flesh that does not change color when cut. The stem grows up to 16 cm long: it is yellowish near the top, brown elsewhere, has a reticulate texture, and mycelium covers its base.
This species has only been documented in western North America. Its fruiting bodies grow in mixed coastal forests during the fall, typically occurring singly or in small groups. It is edible, but its taste is considered inferior to that of other edible boletes such as B. edulis, which it is often mistaken for.
