Mycoparasitism by three species of Diplococcium (Hyphomycetes)

The interactions between three species of Diplococcium and their respective host fungi were investigated using light and transmission electron microsc opy. Two types of interactions were detected: D. clarkii and D. clavariarum , colonizing fruit bodies of basidiomycetes, produce appressoria with protr usions into the cell walls of the host fungi. The host reacts by apposition of secondary wall-like material at the site of the interaction. Hyphae of D. parcum, a species reported from wood and bark, were encircled by hyphae of another fungus, probably belonging to a species of Tulasnella. Since D. parcum could not be cultivated in pure culture, this association between bo th fungi indicates that D. parcum was parasitic on hyphae of the presumed T ulasnella species.