Figs from: http://nordicmicroalgae.org/taxon/Scrippsiella%20trochoidea
A. Scrippsiella cells B. Scrippsiella cysts
Photographer/artist Mats Kuylenstierna
Scrippsiella trochoidea are small to medium sized pear-shaped cells that are 16-36 µm long and are 20-23 µm wide. The epitheca, the top half of the cell, is conical with an apical horn (in contrast to Alexandrium and Heterocapsa) that is often clear while the hypotheca, the bottom half of the cell, is round with no projections or horns (in contrast to Gonyaulax). Their cingulum, or girdle band, is median, wide and strongly excavated. Scrippsiella has chloroplasts and does not grow in chains.
Their distribution is in estuarine, neritic, and cosmopolitan in temperate waters. Scrippsiella may form blooms in summer. They are not known to be toxic. Scrippsiella forms spherical to ovoid calcareous cysts.
Cells are often confused with other small, round, brown dinoflagellates including Gonyaulax spinifera, Alexandrium, and Heterocapsa.
SoundToxins, a diverse partnership of Washington state shellfish and finfish growers, environmental learning centers, Native tribes, and Puget Sound volunteers, is a monitoring program designed to provide early warning of harmful algal blooms and Vibrio parahaemolyticus events in order to minimize both human health risks and economic losses to Puget Sound fisheries.