Fragilidium sp. syn Helgolandinium sp., Goniodoma sp.

Cells are fragile as the name implies. Ecdysis is common under stress where the thecal plates appear as a halo surrounding the cell. See Tomas p.520-521, Taxonomic References. This species is not commonly identified in our whole water samples, but does appear in the Chesapeake Bay on a regular basis. 

Dinoflagellates