First finding of Plumatella vaihiriae (Hastings, 1929) (Bryozoa, Phylactolaemata) in Europe.

The aim of this study is to describe the taxonomical aspects, the biology and ecology of P. vaihiriae collected from Italy. This species was sampled from a pond of ‘‘Bosco di Policoro’’ (South of Italy), and a tropical fish farm (Central Italy). In the pond of Policoro the Plumatella vaihiriae colonies grew with those of P. fungosa and of a Victorellidae. In the glass tank of the fish farm was found only P. vaihiriae, while in the sedimentation pond large colonies of P. casmiana and Plumatella sp were also present. Many mites of two species, which belong to Oribatidae and Halacaridae, were found only on the colonies collected in the glass tank, and in the same tubules seriously damaged statoblasts were present. During the maturation of the damaged immature statoblasts, the remaining material has been organized in an aberrant way. The two species are both predators. Although there are few findings, Plumatella vaihiriae has a widespread distribution. The finding of P. vaihiriae in Italy is of great importance, because it expands the distribution area of the species to include the ?European zone. This species has wide ecological valency for salinity, pH and transparency, but appears to be a stenothermic species. The presence of P. vaihiriae in the Italian habitats could be due to importations by migratory birds at Policoro and by tropical fish in the fish farm.