Prorocentrum triestinum (J.Shiller 1918) syn Prorocentrum redfieldii, Prorocentrum pyrenoideum
Appearing like a small P.micans, it is widely distributed in Northern waters from Europe's North Sea, the Irish Sea and in the Mediterranean. It has also made it across the Atlantic to the Nantuckett Sound area and into Falmouth Harbor at Cape Cod. Each cell has only on chloroplast. It is 6-11µ in diameter and 18-22µ long.