Calcareous sponges of the Netherlands (Porifera, Calcarea)

The taxonomy of calcareous sponges occurring in the Netherlands is reviewed, using field observations of live individuals, microscopical examination of individual skeletons and study of the breeding cycle. This led to the conclusion that a new species had to be erected and other species reidentified. The common calcareous sponges in the Netherlands are found to be: Leucosolenia variabilis (Haeckel, 1872), Scypha ciliata (Fabricius, 1780) and Scypha scaldiensis n.sp