Gymnodinium is a genus of dinoflagellate

Dinoflagellate

The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...

s. It is one of the few naked dinoflagellates, or species lacking armor (cellulosic plates). Since 2000, the species which had been considered to be part of Gymnodinium have been divided into several genera, based on the nature of the apical groove and the biochemistry (specifically, the identity of the main carotenoid

Carotenoid

Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...

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• Gymnodinium sensu stricto
• Akashiwo
• Karenia
  Karenia (dinoflagellate)
  Karenia is a genus of 12 species of dinoflagellates which were formerly included in the genus Gymnodinium.A number of species cause red tides, including Karenia brevis off the coast of Florida and Karenia mikimotoi which was first described in Japan, but is now found in the Atlantic ocean as well,...
  
  
• Karlodinium
  Karlodinium
  Karlodinium is a genus of Alveolata.It includes the species Karlodinium veneficum....
  
  
• Takayama