Diversity and distribution of frehswater molluscs of Comunidad de Madrid (Spain)

Abstract

In this study of freshwater molluscs carried out in Comunidad de Madrid we cite the presence of 33 species, of which 25 are gastropods and eight bivalves. Twentythree of these species were previously reported in this area although most of them with different names either because they are synonyms or because they were determinated erronoeusly. The 33 species were identified from a total of 463 samples together with the specimens preserved at the Museo Nacional de Ciencias Naturales. Taxonomical data and short descriptions, as well as information about the habitats in which they were found is given for the 33 species. We also indicate if they were previously reported in the area and names given by authors. According to the bibliographic data used, a total of nine species are cited for the first time in the region: Pseudamnicola (Pseudamnicola) subproducta, Pseudamnicola (Corrosella) hinzi; Lymnaea stagnalis; Stagnicola palustris; Gyraulus (Gyraulus) chinensis, Gyraulus (Torquis) laevis, Ferrissia (Pettancylus) clessiniana, Oxyloma (Oxyloma) sarsii and Pisidium subtruncatum. Among the previous records, it is worth mentioning that it was not possible to locate “Islamia”coronadoi, Anisus (Disculifer) vortex and Segmentina nitida. Stagnicola palustris, is reported for the first time although only shells were found. Two species, Potamopyrgus antipodarum and Gyraulus chinensis, are alien species. The first of those two species is considered as invasive and presents a wide distribution. Although Lymnaea stagnalis and Oxyloma (Oxyloma) sarsii were only observed in a garden center, we cite them here because there is the possibility that they might accidentally spread out into natural habitats of the region.