''Karlodinium ballantinum'' is a species of unarmored
dinoflagellate
The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...
s from the genus ''
Karlodinium
''Karlodinium'' is a genus of athecate dinoflagellates that lives worldwide. They are often toxin producing, and compared to the other members of the Kareniaceae, are fairly small at <8-15 μm diameter. They are also able to form intense ''. It was first isolated from the Australian region of the
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...
. It is small-sized and is characterized by its very short apical groove. It is considered potentially ichthyotoxic.