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.
Diatoms, Gyrosigma spectabile, marine microalgae, species diversity