Taxonomists revise species descriptions and classifications as
scientific techniques improve. Karenia brevis, the new name for
Florida's red tide organism, has undergone several taxonomic
Karenia brevis (Davis) G. Hansen & Moestrup is the
new name for Florida's red tide organism. The genus
Karenia was created to honor Dr. Karen Steidinger of the
Fish and Wildlife Research Institute.
Taxonomy, the science of identification and classification, is a
dynamic discipline in which conclusions change as advances in
technology result in new information. Taxonomists revise species
descriptions and classifications as improved techniques enable them
to identify or clarify significant characteristics. Assigning the
Florida red tide organism to the correct taxonomic category is
especially important because the toxic dinoflagellate can produce
algal blooms with harmful effects on public health and marine
resources. The need to reclassify it has been recognized since
The genus Karenia was
established in November 2000 by Gert Hansen and Øjvind Moestrup of
the University of Copenhagen (Daugbjerg et al. 2000) to honor Dr.
Karen Steidinger of the Fish and Wildlife Research Institute
(FWRI). The type species for the genus is Florida's red tide
organism, Karenia brevis (Davis) G. Hansen & Moestrup.
Ptychodiscus brevis (Davis) Steidinger 1979 and
Gymnodinium breve Davis 1948 are two prior names for
Karenia brevis =
Ptychodiscus brevis = Gymnodinium
1948: Gymnodinium brevis was named by
Charles C. Davis from cells collected during a red tide event in
Florida in 1946-1947. The name was later corrected to
Gymnodinium breve so the genus and species names would
agree. Gymnodinium is neuter and brevis can be either
masculine or feminine. Therefore, the species epithet
"brevis" was changed to "breve", which is neuter,
to fit the genus name.
1979: Steidinger (1979) transferred the species
to Ptychodiscus because of the prominent apical carina,
cingular thecal ridges, and a resistant cell covering. In addition,
the ultrastructure of the cell covering did not agree with that of
G. fuscum, the type species for the genus
1989: At the 4th International Conference on
Toxic Marine Phytoplankton, held June 26-30, 1989, in Lund, Sweden,
several papers were presented on gymnodinioids, including what was
then termed G. breve (Graneli et al. 1990). Participants
at the conference agreed that the original name, Gymnodinium
breve, would be used until the type species of
Gymnodinium, Gyrodinium, Balechina, and
Ptychodiscus were investigated further to adequately
characterize morphology, ultrastructure, biochemistry, and other
variables. This same consensus had been reached two weeks earlier
at the Taxonomy and Biology of Dinoflagellates and Other Harmful
Phytoplankton Workshop, held June 9-13 at Sherkin Island Marine
Laboratory in County Cork, Ireland. At both the Sherkin Island
workshop and the Lund conference, Steidinger (1990) suggested the
use of pigments and apical grooves as diagnostic characters for the
gymnodinioids that contain fucoxanthin-derived pigments. In a paper
published the same year as the Lund conference, Steidinger et al.
(1989) described the use of conservative morphological characters,
such as the apical groove and sulcal intrusion, to separate the
related species within the Gymnodinium/Gyrodinium
2000: Evidence for the new genus and species
based on morphology, ultrastructure, thecal polysaccharides,
pigments, toxins, and rDNA molecular analyses was presented at the
IXth International Conference on Harmful Algal Blooms, held
February 7-11, 2000, in Hobart, Tasmania, Australia. The title of
the talk was "Evidence for a New Genus Within the Gymnodiniales
from Different Datasets" by A.J. Haywood, K.A. Steidinger, E.W.
Truby, G. Kirkpatrick, T. Suzuki, I. Garthwaite, and L.
Early in 2000, Danish scientists Gert Hansen and Øjvind Moestrup
were also working on what was known as Gymnodinium
mikimotoi and Gyrodinium aureolum. Based on their
studies of the organisms, they came to a similar conclusion about
the need for a new genus. The genus Karenia was
established the following November by Hansen and Moestrup
(Daugbjerg et al. 2000). The classification was based on the cell's
fucoxanthin-derived pigments (19'-hexanoyl-oxyfucoxanthin and/or
19'-butanoyl-oxyfucoxanthin), a straight apical groove (unlike
Gymnodinium's), and the absence of a nuclear capsule or
envelope chambers. In contrast, Gymnodinium F. Stein
emend. G. Hansen & Moestrup is characterized by a
counterclockwise, horseshoe-shaped apical groove and has a nuclear
envelope with vesicular chambers (Daugbjerg et al. 2000, Hansen et
al. 2000). The type species for Gymnodinium is G.
fuscum (Ehrenberg) F. Stein. The genus Gyrodinium
Kofoid & Swezy emend. G. Hansen & Moestrup is characterized
by an elliptical apical groove and a cell covering with
longitudinal striae; its type species is G. spirale
(Bergh) Kofoid & Swezy.
Amazingly, K. brevis isolated as a clonal culture from
Johns Pass, Florida, in 1953 by William B. Wilson remains viable
today, and its rDNA has been sequenced. This sequence and the
sequences for isolates from 1996 are available through GenBank, a
national resource for all publicly available DNA sequences. The
1953 and 1996 isolates are the same, and both are from Florida
IMPLICATIONS FOR RELATED SPECIES
In the paper establishing the genus, two other dinoflagellates
were reclassified to Karenia. Gymnodinium
mikimotoi is now K. mikimotoi (Miyake & Kominami
ex Oda) G. Hansen & Moestrup (Gymnodinium nagasakiense
is considered a synonym for K. mikimotoi), and
Gymnodinium sulcatum is now K. sulcata (Chang) G.
Hansen & Moestrup. Since publication of the Daugbjerg et al.
(2000) paper, two more Karenia species have been named:
K. longicanalis Yang, Hodgkiss & G. Hansen (Yang et
al. 2001) and K. digitata Yang, Takayama, Matsuoka &
Hodgkiss (Yang et al. 2000). K. sulcata, K.
longicanalis, and K. digitata were described based on
morphology, without molecular and/or ultrastructure analyses.
Additions to the genus Karenia are likely as taxonomic
investigations continue and as other species are more accurately
characterized. Proper identification and classification are
important to help assess potential risks associated with an algal
Daugbjerg, N., Hansen, G., Larsen, J., and Moestrup, Ø. 2000.
Phylogeny of some of the major genera of dinoflagellates based on
ultrastructure and partial LSU rDNA sequence data, including the
erection of three new genera of unarmoured dinoflagellates.
Graneli, E., Sundstrom, B., Edler, L., and Anderson, D.M.
(Eds.). 1990. Proceedings of the 4th International Conference on
Toxic Marine Phytoplankton. Elsevier, New York.
Hansen, G., Moestrup, Ø., and Roberts, K. 2000. Light and
electron microscopical observations on the type species of
Gymnodinium, G. fuscum (Dinophyceae). Phycologia
Steidinger, K.A. 1979. Collection, enumeration and
identification of free-living marine dinoflagellates. In: Toxic
Dinoflagellate Blooms (Taylor/Seliger, Eds.), pp. 434-442.
Steidinger, K.A. 1990. Species of the
tamarensis/catenella group of Gonyaulax
and the fucoxanthin derivative-containing gymnodinioids. In: Toxic
Marine Phytoplankton: Proceedings of the 4th International
Conference on Toxic Marine Phytoplankton (Graneli, E., Sundstrom,
B., Edler, L. and Anderson, D.M., Eds.), pp. 11-16. Elsevier, New
Steidinger, K., Babcock, C., Mahmoudi, B., Tomas, C., and Truby,
E. 1989. Conservative taxonomic characters in toxic dinoflagellate
species identification. In: Red Tides: Biology, Environmental
Science, and Toxicology (Okaichi, T., Anderson, D.M., and Nemoto,
T., Eds.), pp. 285-288. Elsevier, Amsterdam.
Yang, Z.B., Hodgkiss, I.J., and Hansen, G. 2001. Karenia
longicanalis sp. nov. (Dinophyceae): a new bloom-forming
species isolated from Hong Kong, May 1998. Bot. Mar. 44,
Yang, Z.B., Takayama, H., Matsuoka, K., and Hodgkiss, I.J. 2000.
Karenia digitata sp. nov. (Gymnodiniales, Dinophyceae), a
new harmful algal bloom species from the coastal water of west
Japan and Hong Kong. Phycologia 39(6):463-470.
A groove located at the anterior part of the cell extending
posteriorly on both the ventral and dorsal sides. On the ventral
side, it does not go any further than the sulcus.
The anterior overhanging process of K. brevis that is
ventrally directed on a K. brevis cell. In most armored
dinoflagellates, this structure is a hole at the top of cell.
The cellular organelle that contains chlorophyll and where
photosynthesis takes place.
cingulum (also called the girdle or transverse
A furrow encircling the cell.
Longitudinal ridges in the cingulum.
A brownish accessory pigment used in capturing energy.
The whiplike tail protruding from the sulcus. This tail acts like
a rudder and steers the cell.
Neither feminine nor masculine.
Permanent nuclear envelope and permanent condensed chromosomes
where deoxyribonucleic acid (DNA) is stored and replication takes
The longitudinal area on the ventral surface of the cell that
forms a somewhat pronounced furrow or depression that houses the
theca (also called cell covering or cell
Multiple membrane layers that encompass the whole cell; contains
vesicles, which are small, bladderlike cavities sometimes filled
The ribbonlike tail encircling the cell within the cingulum. When
beating, this propels the cell.
Refers to the fine internal morphology of the cell.
Polygonal structures that are membrane bound and usually
compressed against one another in the cell covering (theca) or in
Dr. Steidinger's experience is in
dinoflagellate taxonomy, life cycles, and ecology, particularly
with regard to toxic species and the management of shellfish
resources. Her interests are the dynamics of harmful algal blooms
and how life cycle strategies and species adaptations allow certain
dinoflagellates to exploit their environment on temporal-spatial
scales. Other interests include working toward the development of
management options for harmful algal blooms and for reducing their
risk to humans and living marine resources.