On the identity of the type species of the genus Ceratium Schrank (Dinophyceae), with notes on C. hirundinella

The genus Ceratium Schrank (Dinophyceae) was originally described with two species, both of which have been indicated as the type of the genus in the modern literature. Ceratium pleuroceras Schrank is not a dinoflagellate and should not be regarded as the type. We argue that the other species, C. tetraceras Schrank, should be regarded as the lectotype, and in turn synonymous with the freshwater species C. hirundinella (O.F. Muller) Dujardin. In practice, this means that C. hirundinella becomes the type of the genus. Citations of either Schrank or Bergh as authors of the combination C. hirundinella are most often found in the literature, but are incorrect. Ceratium furcoides (Levander) Langhans, presently recognized as an independent species, has been included by many workers in C. hirundinella; much information referred to C. hirundinella may, therefore, pertain instead or also to C. furcoides.JNICT-PRAXIS XXI/BD/3887/9