Pseudothecium

A pseudothecium is a fungal fruiting body, specifically a type of ascocarp, that develops within a pre-formed locule or cavity in host tissue, rather than being borne on a surface or within a stroma. It is characteristic of the class Dothideomycetes and other related fungal groups. Unlike a true ascocarp, the pseudothecium is not initiated by the fungus itself but is often formed within a cavity created by the breakdown of host cells or by other fungi.

The structure of a pseudothecium is typically flask-shaped or globose and possesses a distinct opening called an ostiole through which ascospores are released. Within the pseudothecium, asci, the spore-bearing cells, develop. These asci contain ascospores, which are the asexual reproductive units in this context. Pseudothecia are often dark and leathery in texture. They are commonly found on plant material, where they play a role in the dispersal of fungal pathogens or saprobes. The formation of pseudothecia is an important taxonomic feature for identifying certain fungi.