The centric diatom Coscinodiscus bouvet Karsten is a distinctive Antaretic endemic species whose distribution can be assessed reliably from a large body of literature. It appears to be typically neritic, but has also been found as a dominant species in the Scotia Sea during the period of Discovery Investigations. It is suggested that this widespread occurrence of C. bouvet in oceanic waters reflects changes in the advection of the species from ‘seed populations’ in Bransfield Strait. Changes in grazing pressure, resulting from varying krill abundance, are discounted. The species is re-described in order to rectify inadequacies in Karsten’s (1905) diagnosis.