Nederlandse mollusk, ja of nee? Scherpere opnamecriteria voor de recente lijst van de Nederlandse mariene weekdierfauna.

The Dutch Species Catalogue provides a current and comprehensive overview of Dutch biodiversity (http://www.nederlandsesoorten.nl/node/374). As to recent marine molluscs, however, the catalogue is not clear enough how to deal with species of which only fresh shells have been found. De Bruyne et al. (2013) consider species of which living specimens or very fresh shells, i.e. shells with soft parts (tissue, ligament, periostracum), have been found as belonging to the recent Dutch marine mollusc fauna. The authors propose to include conditionally also species known from fresh shells, i.e. shells which are not fossilized, more or less transparent and/or with original co Jours. The find of fresh shells indicates that a species most probably Jives in the near surroundings (De Bruyne, 2004: 14; Cadée & Wesselingh, 2005: 47-50). With the present admission criteria the Dutch biodiversity runs a risk to be underestimated.