Studies on the Genera Gyrosigma and Pleurosigma (Bacillariophyceae). Rediscovery of a "lost" species: Gyrosigma spectabile (Grunow ex Peragallo) Cleve

Only one verifiable specimen of Gyrosigma spectabile (Grunow ex Peragallo) Cleve is on record. Herein we describe flourishing populations from Brazil that have been sampled over a period of several years. These samples give a good overview of the morphology of this species: the single specimen previously illustrated corresponds to an ontologically early stage, whilst mid-range specimens superficially resemble Gyrosigma balticum (Ehrenberg) Rabenhorst. This rediscovery illustrates the poor insight into existing species diversity — especially of (sub)tropical marine littoral diatom floras.