Gyrodinium impudicum sp. nov. (Dinophyceae), a non toxic, chain-forming, red tide dinoflagellate

Abstract A new chain-forming dinoflagellate Gyrodinium impudicum sp. nov., Gymnodiniaceae, is described from Valencia Harbour, Ria de Vigo (Spain) and Fusaro Lagoon (Italy). The cingulum is a descending left spiral, displaced between 1/3–1/4 of the total length of the cell and the sulcus is without torsion, two reasons why the new species is assigned to Gyrodinium. This red tide organism has been misidentified in several previous papers as Gymnodinium catenatum Graham or Polykrikos schwartzii Butschli. It differs from G. calenatum in cell shape and size of the acrobase. No paralytic shellfish poison (PSP) was found. G. impudicum has caused blooms in several areas but no associated harmful effects have been reported.