Karenia brevis was named for Dr. Karen A. Steidinger in 2001, and was previously known as Gymnodinium breve and Ptychodiscus brevis. Karenia brevis is a marine dinoflagellate common in Gulf of Mexico waters, and is the organism responsible for the "tides" (coastal infestations) termed red tides that affect Gulf coasts—of Florida and Texas in the U.S., and nearby coasts of Mexico. It is the source organism for various toxins found present during such "tides," including the eponymously named brevetoxins.