Abstract: The author considers especially the sporal, anatomical and cytological characters of the genera Karstenella Harmaja and Pseudorhizina Jach. to warrant the establishment of a new mono typic family for each: Karstenelloceae Harmaja and Pseudorhizinaceae Harmaja. Certain characters relevant to the family level taxonomy have been observed by the author in both genera. Features apparently diagnostic of the family Karstenellaceae are the p resence of two nuclei in the spores, the lack of a cyanophilic perispore in all stages of spore development, the simple structure of the excipulum which is exclusively composed of textura intricata, and the subicular characters. The genera of the Pezizales with tetranucleate spores are considered to form three different families on the basis of both sporal and anatomical differences: Helvellaceae Dum., Pseudorhizinaceae and Rhizinaceae Bon. The lack of a cyanophilic perispore in the mature spores and the simple structure and thick-walled hyphae of the excipulum are important distinguishing features of the family Pseudorhizinaceae. Comparisons are given between Pseudorhizinaceae and the two other families.