De grondwaterslak Bythiospeum husmanni (Boettger, 1963) in Nederland (Gastropoda Prosobranchia: Hydrobiidae)

During archaeological investigations in the village of Kesteren, in the central part of the Netherlands, a soil sample was taken at a depth of about 70 cm (fig. 1) for biological analyses. The three litres of fine sand with some clay contained nine empty fresh-looking shells of the groundwater snail Bythiospeum husmanni. This species was hitherto known only from the groundwater of the Ruhr valley, Germany, c. 150 km ESE. of the Dutch record. In the same sample one valve of the groundwater ostracod Pseudocandona zschokkei was found. Possibly these animals have lived at Kesteren in situ in groundwater of the sandy and gravelly alluvial deposits of the Rhine valley, between 2800 years ago and Recent times (recently the watertable was lowered).