Gastrosuillus, once considered a distinct genus, has been shown with molecular analysis to be a recent evolutionary derivative of Suillus. Fuscoboletinus, described by Pomerleau and Smith in 1962, has also been subsumed into Suillus.
Gastrosuillus was formerly considered a distinct genus but has since been proven through molecular analysis to be a recent evolutionary descendant of Suillus. Likewise, Fuscoboletinus, initially described by Pomerleau and Smith in 1962, has also been subsumed into the Suillus classification.