Gymnodinium sanguineum Hirasaka, 1922
Species Overview:
Gymnodinium sanguineum is an unarmoured, marine, planktonic dinoflagellate species. This cosmopolitan species is a red tide former that has been associated with fish and shellfish mortality events.
Taxonomic Description:
Gymnodinium sanguineum is an athecate species; i.e. without thecal plates. This species is highly variable in size and shape. Cells are large, slightly dorso-ventrally flattened and roughly pentagonal (Figs. 1-4). An apical groove is present (Fig. 2). Cells range in size from 40-80 µm in length (Hirasaka, 1922, Lebour, 1925, Dodge, 1982, Fukuyo et al., 1990, Hallegraeff, 1991, Steidinger and Tangen, 1996).
The epitheca and hypotheca are nearly equal in size. The epitheca is rounded and conical, and the hypotheca is deeply indented by the sulcus creating two posterior lobes (Figs. 1-4). The median cingulum is left-handed and displaced 1-2 times its width (Figs. 2,3). The sulcus does not invade the epitheca, but expands posteriorly into the hypotheca (Hirasaka, 1922, Lebour, 1925, Dodge, 1982, Fukuyo et al., 1990, Steidinger and Tangen, 1996).
Morphology and Structure:
G. sanguineum has numerous large, spindle-shaped, reddish-yellow-brown chloroplasts radiating from the center of the cell. The large nucleus is slightly off-center (Fig. 4). Cells can vary from heavily pigmented to pale yellow or nearly colorless (Hirasaka, 1922, Lebour, 1925, Dodge, 1982, Fukuyo et al., 1990, Steidinger and Tangen, 1996). Mixotrophy has been observed for this species: in the Chesapeake Bay G. sanguineum preys on ciliate protozooplankton (Bockstahler and Coats, 1993).
Reproduction:
G. sanguineum reproduces asexually by binary fission; cells divide obliquely during mitosis (Dodge, 1982).