A new marine gastropod species from S. Europe, Nodulus spiralis spec. nov. (Prosobranchia: Rissoacea)

In a sample of nearly three litres of shell grit, collected in September 1984 by Dr. W.M. Wagner in southern France, on the peninsula of Antibes (Department of Alpes-Maritimes), about 2000 fresh looking, partly even living, specimens of Nodulus Monterosato, 1878, were found. There proved to be a conspicuous dimorphism among these shells, not only as regards habitus and sculpture, but also as regards height. Apparently, two separate species were represented in the material. This conclusion was supported by a study of material of Nodulus from other localities in southern Europe. One of the species is here described as new. For collections the following abbreviations are used: LH, J. van der Linden, Den Haag; RMNH, Rijksmuseum van Natuurlijke Historie, Leiden; VL, A. Verduin, Leiden; WA, W.M. Wagner, Amsterdam; ZMS, Zeebiologisch Museum, Scheveningen.