The Chaetophorales (Chlorophyceae)–a taxonomic revision at family level

Abstract

The Chaetophorales (Chlorophyceae) consist of filamentous green algae that were mostly described directly from natural samples by light microscopy. However, the descriptions were often based on morphological characters that are either homoplasious or sensitive to environmental factors. This clearly prevents proper identification of several chaetophoralean taxa and highlights the need for taxonomic revision at different taxonomic levels. In the present study, we focused on revision of the Chaetophorales at the family level. We used a well-resolved molecular phylogeny to re-evaluate morphological characters in the Chaetophorales under clearly defined laboratory conditions. We identified five morphological characters that permitted unambiguous identification of most chaetophoralean families, and used these characters to establish a new family, the Fritschiellaceae (fam. nov.), and emend the Chaetophoraceae Greville 1824. Knowledge gained from this study lends additional weight to the current classification of the Chaetophorales and may serve as an example for taxonomic revisions of other complex filamentous algae.