Synonym :
Gonyaulax (Protogonyaulax) catenella

Morphological Characteristics :
The organism may occur as single cells (similar to A. fundyense), but more often in characteristic short chains of 2, 4 or 8 cells. The cells are often compressed both in the anterior and posterior ends. The first apical plate is connected with the triangular apical pore plate.

Size of Specimen :
20-25 mm (L), 25-32 mm (W)

Distribution :
Have been found and caused algal blooms in the west coast of N. America, Japan and Australia. Widespread in the Northern Hemisphere. Caused red tide in Junk Bay and the eastern waters of Hong Kong in 1989. Also, unusually high toxicity levels were detected in shellfish samples during the spring of 1990, mainly collected from the eastern and southern waters of Hong Kong The event in 1989 resulted in suspension of shellfish sale for almost two weeks.

Cysts (see plates) of the organism were found widely existed in the sediments of Hong Kong, Dapeng Bay and Daya Bay.

Major Limiting Factors :
Growth is stimulated by the supply of ammonium and inorganic nitrogens. Optimal growth at cool temperature (17-23°C), medium light illumination (3500-4000 lux) and high salinity (26-32 %o).

Toxicity :
Closely related to Paralytic Shellfish Poisonings (PSP). Caused high toxicity in Japan, N. America and Europe. Unusually high toxicity in Hong Kong in 1989-90.