The genus Skeletonema Greville emend.Sarno et Zingone is one of the most widespread among the plankton marine diatoms.It can bloom in coastal waters and is one of the most abundant plankton diatoms all over the world.Members of the genus Skeletonema are very hard to identify using a common light microscope.It happens due to small sizes of the cells and to the fact that many diagnostic morphological characters are shared by several species.