Morphology and taxonomy of Cyclotella elentarii spec. nov., a newly described centric diatom from a New Zealand lake.

The morphology and systematics of a new centric diatom (Cyclotella elentarii from Lake Monowai, New Zealand) are presented. The morphological variation and ultrastructure as revealed by light and electron microscppy are described. The new species is characterized by a flat central area with a colliculate-radiate structure without central fultoportulae and a marginal area with areolate and depressed striae bearing short spines. The marginal fultoportulae are positioned on the mantle between the costae on every two striae together with a single rimoportula. In some specimens a delicate central rosette may be visible. Differences with similar taxa in the genus Cyclotella and the delimitation of the stelligeroid group are discussed.