A redescription of the tidal pool dinoflagellatePeridinium gregariumbased on re-examination of the type material

The type material of Peridinium gregarium Lombard et Capon, originally described from tidal pools in Southern California has been re-examined. Two of the three slides that have been deposited in the Herbarium, California State University, contained two dinoflagellate taxa viz. P. gregarium and Scrippsiella hexapraecingula Horiguchi et Chihara. These observations have clarified the nomenclatural confusion that has existed between these two taxa. Based on new observations of the type material, the thecal arrangement of P. gregarium has been emended and we propose the transfer of this species to the genus Scrippsiella with the new name, Scrippsiella caponii.