The fungus Xylobolus frustulatus grows exclusively on dead oak wood and causes a characteristic pocket rot. It is rare in Bohemia and Moravia but common in southern Slovakia. The paper discusses its distribution, morphology, and host specificity.
Kotlaba F. (1967): Xylobolus frustulatus (Pers. ex Fr.) P. Karst. in Bohemia. – Česká Mykologie 21(2): 117–119.