Acarospora mayrhoferi (Acarosporaceae), a new species from the European Alps (Italian part) and the French Massif Central

Acarospora mayrhoferi is described from the Italian parts of the Alps and from the French Massif Central. It is a lichenicolous lichen, an obligate parasite on Dimeleana oreina, eventually forming its own independent brown thallus of flat black-edged areoles. The simple ascospores are sometimes globose 2 x 2 mu m. often broadly ellipsoid 3 x 2 mu m or ellipsoid 4-5 x 2 mu m. The hymenial gel is I+ blue. It belongs to the morphological Acarospora anatolica group. A key is supplied for six similar parasitic species of Acarospora.