Waarom worden Blindslak (Cecilioides acicula) en Aardschijfje (Lucilla scintilla) zelden samen gevonden?

Analysis of six reports on independent inventories of land snails in the Netherlands and Flanders showed that the subterranean species Cecilioides acicula and Lucilla scintilla only rarely occur together at the same locality. Because both species are quite rare, the few localities harbouring both species (2 out of 914) could be explained by chance. However, apparent mutual exclusion of the two species in small areas leaves the possibility of a causative biological phenomenon. Occurence of both species in large numbers reported for one locality in Obino (Switzerland) pleads against aggressive competition between the two species. Perhaps in the Netherlands and Flanders specific non-biotic characteristics of the soil (e.g. structure, lime) or biotic components therein (e.g. roots of certain plants, moulds) contribute to the apparent mutual exclusion of the two species.