On the taxonomic identity of Diadesmis confervaceoides Lange-Bert. et U. Rumrich (Bacillariophyceae)

Diadesmis confervaceoides was separated from D. confervacea based on differences in both the fine structure of the proximal external ends of the raphe (which have central pores) and the shape of the central area, as well as the absence of linking spines on the junction of the valve face and mantle. Based on observations of individuals of D. confervacea that grow in Rodriguez Stream (Buenos Aires Province, Argentina), and having compared them with observations carried out by other authors both in natural populations and clonal cultures, it is proposed that D. confervaceoides be considered as a synonym of D. confervacea. This proposal is a consequence of the polymorphism of frustules integrated in different positions of cell chains, a phenomenon that has been overlooked until recently.