Nieuwe Polysiphonia -soorten voor België en Noord-Frankrijk, met een gereviseerde determineertabel voor de soorten van het geslacht Polysiphonia in deze regio

The recent Seaweed Flora of Belgium and Northern France (Coppejans 1998) mentions six species of Polysiphonia for the region. Recent collections near Calais and Oostende have revealed the occurrence of three additional species: P. brodiaei and P. denudata from Calais harbour, P. senticulosa from Oostende. The latter species is regarded as an alien introduction that may have been imported with oysters, probably from British Columbia (Canada). P. brodiaei and P. senticulosa are described and illustrated in some detail, and a revised key to the Polysiphonia species of the region is given.