Rarely reported dinoflagellates of the genera Ceratium, Gloeodinium, Histioneis, Oxytoxum and Prorocentrum (Dinophyceae) from the open southeast Pacific Ocean

Rarely reported dinoflagellates of the genera Ceratium, Gloeodinium, Histioneis, Oxytoxum and Prorocentrum from a ~8000 km transect between the Marquesas Islands Archipelago and the Chilean coast are briefly described and illustrated. Nineteen species of the genus Oxytoxum and seven species of the genus Histioneis were identified to species level. Photographic records of Histioneishyalina and H. cf.pulchra are for the first time reported. One specimen ascribed to Histiophysis sp., a genus never reported since the first description, is illustrated. Beyond the singlecell specimens of Prorocentrum, a colonial behavior was observed. A small species, identified as Prorocentrum dentatum, was encountered forming rows. Colonies of pairs of ellipsoidal or sphaerical cells embedded in a hyaline matrix have been ascribed toGloeodinium marinum. Ceratium lanceolatum is for the first time reported in the South Pacific Ocean since the first description. Photographic records of Ceratium carnegiei, C. divaricatum and C. lanceolatum are reported.