A new Ceratium species (Dinophyceae) from Lake Doirani, Macedonia, Greece

A new taxon of Ceratium is described from Lake Doirani, Greece. It is proposed as a new species and named Ceratium monoceras. It differs morphologically from known species of Ceratium by having only one horn, the apical horn. Accordingly, the vegetative cells form cysts that have only one spine. Details of its ecology and occurence are given.