Linzer biol. Beitr. 38/1 47-54 21.7.2006 A new species of the European freshwater bryozoan fauna: Plumatella similirepens WOOD, 2001 (Bryozoa, Phylactolaemata) M.I. TATICCHI, G. PIERONI & A.C. ELIA Abstract: Plumatella similirepens WOOD, 2001 colonies were collected during May 2001 and June 2004 adhering to wooden barriers inside a farming tank and to stones inside sedimentation tank of a trout farm (Quinto, Treviso, Italy). Until now, this species is recorded only from two hatcheries of Illinois USA. In this study we describe Plumatella similirepens WOOD, 2001, which is a new species for Europe. At the same time we discuss on the differences between the American and the Italian specimens and also between this species and typical Plumatella repens. K e y w o r d s : Freshwater bryozoans, Phylactolaemata, Plumatella similirepens, Fish farms, Italy. Introduction The freshwater bryozoan Plumatella similirepens WOOD, 2001 was recorded for the first time in Italy in 2004 (TATICCHI et al. 2004). The species was sampled from one of the thirteen trout farms inspected during a research project on PKD (Proliferative Kidney Disease) epidemiology in Italy (CAFFARA et al. 2002; TATICCHI et al. 2004). This is a new species for the European freshwater bryozoan fauna. Previously P. similirepens was reported only from Illinois, USA by WOOD (2001). The Author found it in only two fish farms and so he concludes that "either the fish hatcheries offer conditions particularly suitable for this species, or else that the bryozoans were introduced to the sites along with received shipments of fish". The aim of the present study was to describe the species Plumatella similirepens re- corded from Italy. At the same time, we discuss on the differences between the floato- blasts of the American and Italian specimens and also the differences between P. similirepens and P. repens sampled from the same site and typical P. repens. Material and methods P. similirepens colonies were collected during May 2001 and June 2004 in only one fish farm, where PKD is enzootic along the course of Sile River (Quinto-Treviso). They were adhering to wooden barriers inside a farming tank and to stones inside the sedimentation tank. © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at