Photo from: http://media.nordicmicroalgae.org/large/Protoceratium reticulatum_2.jpg
A. LM, two focal planes; B. LM, cyst; C. SEM, whole cell with ventral pore (arrow).
Protoceratium reticulatum has polyhedral shaped cells with strong reticulations that often mask the plates; cells small to medium, 25-55 µm long, 25-35 µm wide. The epitheca a broad cone with ± straight sides, shorter than hypotheca; hypotheca with straight to convex sides, rounded to squarish antapex with no spines. Cingulum nearly medium, slightly descending. Chloroplasts present and give the cells a deep brown color.
Cells are easily confused with other smallish, round, brown cells including solitary Alexandrium cells and some Gonyaulax species. Populations from South Africa were described as Gonyaulax grindleyi Reinecke which remains a synonym. Cysts, described as Operculodinium centrocarpum (Deflandre & Cookson) Wall (also known as Hystrichosphaeridium centrocarpum Deflandre & Cookson) are spherical with dense ornamentation of tapering spines with hooked tips.
Their distribution is neritic, estuarine; cold temperate to subtropical waters; reported from all oceans. They produce yessotoxins which are toxic to mice when administered orally, but their threat to human health is currently unclear.
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.