We studied the rarely occurring pycnidial conidiomata in three species of the genus Peltigera using electron microscopy (SEM and TEM). Pycnidia are marginal and half-immersed, having unilocular cavities with double-layered walls and slit-shaped ostioles. The conidiophores are composed of sterile basal and very few axial cells, supporting elongated conidiogenous cells. The conidia are produced at their apices by leaving behind phialidic collarettes either at the same level or in a proliferating manner, extending the conidiogenous cells. The study of the ontogeny of the pycnidial conidiomata demonstrates the origin and the gradual development of the characteristic anatomical structures, such as the wall layers, the bursting ostiole, and the non-chambered cavity, which is completely lined by the conidia-forming elements. The combination of these morpho-anatomical details is unique and hence accepted here as ‘Peltigera-type’, in addition to previously recognized pycnidia types (Vobis 1980).

Chaenothecopsis inconspicua is a new anamorphic lichenicolous fungus forming black sporodochia on the thallus of Lecanora expallens. Molecular analysis demonstrates that the new species is positioned in the Mycocaliciales. Although a remarkable diversity of anamorphs was already recognized in Mycocaliciales, it is the first species within this order known to produce sporodochioid conidiomata. Chaenothecopsis inconspicua is currently known from several localities in the northern half of the Netherlands, most often on old Quercus robur trees in villages. A key to the lichenicolous fungi inhabiting Lecanora expallens is provided.