Een eerste slak in het Formerumerwiel, Terschelling

Until recently no molluscs were known to occur in Formerumerwiel, a small lake caused by a dike collapse in 1717 near Formerum on the island Terschelling (the Netherlands). In the autumn of 2007 and 2008 the allochthonous snail Potamopyrgus antipodarum (Gray, 1843), Fam. Hydrobiidae, was located on a particular spot among reed (Phragmites) in the NW-corner of the Formerumerwiel. Nowhere else could I trace this invasive species from New Zealand under similar circumstances in the lake.