De verspreiding van het slakje Leucophytia bidentata in het Deltagebied van Rijn, Maas en Schelde

The pulmonate snail Leucophytia bidentata reaches the northern border of its area in the south-western part of the Netherlands. The species has been found there in 37 localities. It is common in the water system of the Eastern Scheldt, which is characterized by high salinity (16-17‰ Cl’) and which does not function as a rivermouth. In the sea-arms Grevelingen and Western Scheldt the species inhabits the banks of the euhaline parts and intrudes only slightly into the polyhalinicum, reaching its salinity limit already at 15‰ Cl’. Leucophytia bidentata prefers sheltered places around neap tide high-water-mark, under stones in coarse silty sand of a high consistency. The species occurs along dikes as well as on salt-marshes; often it has been found in sheltered corners where flotsam is decomposing.