ABSTRACT: Eight lichenicolous fungi are reported from Ionaspis lacustris in Europe. Three species are described and illustrated in detail: Sagediopsis lomnitzensis (also from Ionaspis odora) and Zwackhiomyces lacustris are new combinations, Verrucaria conturmatula is accepted as the first non-lichenized, lichenicolous member of this genus. A neotype is designated for S. lomnitzensis. A key is provided to species on I. lacustris.

KEYWORDS: Verrucariales, Dothideales, Europe, freshwater lichens

NOMENCLATURAL NOVELTIES:
Sagediopsis lomnitzensis (Stein) Orange, p. 267
Zwackhiomyces lacustris (Arnold) Orange, p. 275