Bacidia neosquamulosa Aptroot & van Herk, a new corticolous lichen species, is described from the Netherlands, where it seems to be rapidly spreading and where it is considered to be a neophytic species. It is also reported from Belgium and Great Britain. It resembles corticolous morphs of the rather variable B. arnoldiana, but differs from this and other species by the longer, conspicuously septate, filiform, curved, macroconidia, the longer ascospores and the squamuloseisidiate thallus.