The first collections of the rare ascomycete Ionomidotis irregularis from the Czech Republic are described and illustrated with colour photos and drawings of the most important microscopic characters. Data on ecology and occurrence at 17 localities throughout Europe including some unpublished data are summarised. Evidently, I. irregularis prefers strongly decayed trunks of Fagus sylvatica as its substrate within the European beech distribution area. In North-eastern Europe, where Fagus is missing, the occurrence of the fungus is documented on decayed wood of several other deciduous tree species (Alnus incana, Betula sp., Carpinus betulus, Ulmus glabra). Because of its strong preferences for unmanaged, old-growth forests, I. irregularis should be considered an indicator and flagship species of such habitats throughout Europe.
Běťák J., Pärtel K., Kříž M. (2012): Ionomidotis irregularis (Ascomycota, Helotiales) in the Czech Republic with comments on its distribution and ecology in Europe. – Czech Mycology 64(1): 79–92.
