Overzicht van de Nederlandse Leptolida (=Hydroida) (Cnidaria: Hydrozoa)

In this paper a review is presented of the Dutch leptolid (= hydroid) fauna (phylum Cnidaria, class Leptolida). The Dutch faunal boundary has been defined by Boschma (1927) and was based on the presence of lightvessels off the Dutch shores. Though the lightvessels have disappeared this formal faunal boundary has been maintained. A total of 146 species, belonging to 87 genera in 38 families, are shortly described and illustrated. 114 species can be considered truly indigenous Dutch species, of which the occurrence within the Dutch faunal boundaries is substantiated by material in collections or records in the faunistic literature. Of seven species either material or convincing records are available but their geographical distribution indicates that they do not form part of the Dutch fauna, whereas of 25 species the distributional pattern indicates that sooner or later they will be may become part of the Dutch fauna.