In this paper descriptions are given of the hyphal structure in the hydnaceous genera Climacodon P. Karst., Creolophus P. Karst., Donkia Pilát, Hydnellum P. Karst., Mycoleptodonoides Nikol., Mycorrhaphium Maas G. (which is introduced as a new genus), Phellodon P. Karst., Sarcodon P. Karst., and Steccherinum S. F. Gray. The following new combinations are proposed: Hydnellum piperatum (Coker) Maas G., Mycorrhaphium adustum (Schw.) Maas G., M. pusillum (Brot. ex Fr.) Maas G., and Steccherinum murashkinskyi (Burt) Maas G.