A new pathogenic polypore on urban trees: The first record of Rigidoporus ulmarius (Rigidoporaceae, Hymenochaetales) in Hungary

The Giant Elm Bracket (Rigidoporus ulmarius) is a widely-distributed necrotrophic polypore species that causes white heart rot in deciduous trees. Despite its recognition as one of the largest species known for forming basidiomata, this perennial polypore had not been documented in Hungary. However, in recent years, two specimens macroscopically resembling this species were collected on old horse chestnut (Aesculus hippocastanum) trees from two different places in Hungary by amateur mycologists. In this study, subsequent morphological and molecular-genetic analyses of these fungal samples confirmed their identity as R. ulmarius. This study represents the first documented occurrence of this plant pathogenic polypore species in Hungary.