Heterocapsa circularisquama is small thecate dinoflagellate
which belongs to Peridiniales. Dr. Horiguchi of Hokkaido University describes
circularisquama as a new species. H. circularisquama looks like
typical spindle shape of dinoflagellates. It has thin plates, and yellow
brownish chromatophores. Cells are 18-30ƒÊm in length, and 12-22ƒÊm in
width. The cell has a deep girdle, comparatively shallow sulcus, and sharp
apex. Typical hypnozygote (cyst) is not known but vegitative cells of H.
circularisquama transform their cells to temporary
cyst when the environmental conditions became unsatisfactory. For the
species identification, body scale morphology should be confirmed.
Numerous endosymbiotoc bacteria were found in cytoplasma and autolysosome of almost H. circularisquama cells.
Photomicrograph of Heterocapsa circularisquama