Previous | Next | Gallery
Scroll down to review gallery images.
The raphe system of this genus is not elevated above the general level of the valve. One species, P. multiseries, is known for producing the neurotoxin domoic acid. Its cells are strongly elongate and rectangular or fusiform and the raphe strongly is eccentric and not raised above the valve.
This genus is planktonic; widely distributed, and inhabits marine waters.