LIGHT AND ELECTRON-MICROSCOPIC OBSERVATIONS ON PROTOCERATIUM-RETICULATUM (DINOPHYCEAE)

Light and electron microscopical observations have been made on the go nyaulacoid dinoflagellate Protoceratium reticulatum (CLAPAREDE et LACH MANN) BUTSCHLI collected close to the type locality of Protoceratium a ceros BERGH, the type species of Protoceratium. Analysis of plate tabu lation shows agreement with Gonyaulax grindleyi REINECKE and supports conspecificity between P. reticulatum, P. aceros and G. grindleyi, the first name having priority. The ultrastructure includes a branched ch loroplast and a centrally located pyrenoid complex. The pusular system consists of one or two sac pusules associated with the flagellar cana ls. The three-dimensional arrangement of the flagellar apparatus is ba sically similar to that of other dinoflagellates except for the presen ce of a single microtubular root associated with the longitudinal basa l body. Each flagellar canal is surrounded by a distinct striated fibr ous collar. The collars are interconnected by two striated connectives . The plate tabulation and fine structure of Protoceratium reticulatum indicate close relationship to the genus Gonyaulax, with minor differ ences in plate tabulation and fine structure. it is suggested to maint ain the genus Protoceratium until the fine structural diversity with G onyaulax is better known.