Butyriboletus
Butyriboletus is a genus of fungi in the family Boletaceae. The genus was circumscribed in 2014 by mycologists David Arora and Jonathan L. Frank to accommodate "butter bolete" species that were shown by molecular analysis to be phylogenetically distinct from "Boletus". "Butyriboletus" contains 21 ectomycorrhizal species found in Asia, Europe, North America and north Africa. The group had earlier been classified as the section "Appendiculati" within the large genus "Boletus". They were given the common name "butter boletes" as the color of their stalk, flesh and pores was similar to that of butter. Genetic analysis published in 2013 shows  that these species are part of a "regius" clade (named for "B. regius"), distinct from the core group of the type species "B. edulis" and relatives within the Boletineae. The narrowing of "Boletus" to this latter group meant that this group would need to be placed in a separate genus, with "Boletus appendiculatus" (now "Butyriboletus appendiculatus") designated as the type species. The genus name itself is derived from the Latin "butyrum" "butter". The butter boletes have red or brown caps, yellow pores and stipes that turn blue when cut or bruised in many species, and olive-brown spindle-shaped spores . Their flesh is usually mild tasting. "Butyriboletus roseoflavus" is a highly regarded edible mushroom sold in markets in southwestern and southeastern China, while two other species—"B. yicibus" and "B. sanicibus"—are eaten to a lesser degree in Yunnan Province. Species. The following species are recognized, though more may yet be described from Japan, Mexico and China.