Phenotypic plasticity in the diatom Cyclotella meneghiniana or a new species?

In a short core (70 cm) from Toolo Bay, a Baltic Sea inlet in the centre of Helsinki, Finland, Cyclotella meneghiniana was found. This diatom showed morphological variation during a period of heavy pollution, especially at depths of 37-38 cm in the core. Light and scanning electron microscope investigations reveal changes in the number of valve face fultoportulae (independent of the relationship between diameter and the number of central fultoportulae), in the shape of the striation and the costae, and in the position and shape of the satellite pores of the mantle fultoportulae. We tentatively interpreted this diatom to be a form of C. meneghiniana, adapted to highly nutrient-rich conditions or other "extreme" environments. Whether the described form is a new species or not is left open for further investigation.