Two species of Ulva (Chlorophyta, Ulvales) are reported from the Netherlands for the first time: U. pertusa is a robust species, to be classified as an alien, originating in the Asian Pacific - it has become abundant in the lower intertidal and sublittoral of the Oosterschelde and in the stagnant lake Grevelingen. U. tenera is a minute species, comparatively recently described from Helgoland; in the SW Netherlands, as in the type locality, it is found in the upper eulittoral of wave-exposed sites. |
