Circa 110 genera of ulvophytes are currently circumscribed, most of which are restricted to the marine environment. Although most of the traditionally circumscribed genera are easily distinguishable based on gross morphological features, DNA sequence data have revealed that many genera are not monophyletic. For example, Pseudendoclonium, a genus occurring in marine, freshwater, and damp terrestrial habitats, is polyphyletic as indicated in several molecular phylogenetic studies (Carlile et al. 2011, Škaloud et al. 2013b), and only for a few species the placement in the family Kornmanniaceae has been confirmed, while other species have other affinities within the Ulvales-Ulotrichales clade. The taxonomy of the genus is further revised in the present treatment, including the description of the new genus Neoclonium to accommodate Pseudendoclonium akinetum.