Validation of Marasmius epidryas (Agaricomycetes), an emblematic arctic-alpine fungus

‘Marasmius epidryas’ is a widely used name for an arctic-alpine saprotrophic fungus specifically associated with dead tissues of Dryas spp. It has never, however, been validly published. In the present paper, the name ‘Marasmius epidryas’ is validated by supplementing the original Kühner’s description with a Latin diagnosis. Full description and illustration of the holotype is provided.