Rindifilum ramosum gen. nov., sp. nov., a new freshwater genus within the Ulvales (Ulvophyceae, Chlorophyta)

The present paper provides a phylogenetic and morphological study of two strains that turn out to represent a new genus and species, Rindifilum ramosum gen. nov., sp. nov., within the family Ctenocladiaceae (Ulvales). Rindifilum ramosum gen. nov., sp. nov. grows in association with the lichenized ascomycetes genus Verrucaria Schrader. Phylogenetic reconstructions based on the rbcL, 18S rRNA and tufA genes showed that the investigated strains belonged to a lineage distinct from those sequenced so far. Moreover, comparisons based on morphological observations revealed no differences between the two strains. The newly genus Rindifilum gen. nov. exhibits a unique combination of morphological features, as the “pear-shaped” cells that develop directly into a “hammer-shaped filament”, making it distinct from all other green algae described so far.