Ultrastructure of the ascus and the ascospores in Pseudascozonus (Pezizales, Ascomycotina)

The ultrastructure of the ascus and the ascospores in Pseudascozonus is described. The top of the ascus opens by a small rather roughly delimited operculum. A circular furrow in the inner ascal wall causes a weakened zone. The development of the ascospore wall shows a simple homogeneous epispore and disappearance of all secondary wall material. In the epiplasm of the ascus a unique type of envelope, surrounding all eight ascospores, is described. Relationship with Ascozonus and Theleboli with 8-spored asci is suggested.