COEXISTENCE OR SPATIAL SEGREGATION OF SOME VERTIGO SPECIES (GASTROPODA: VERTIGINIDAE) IN A CAREX RICH FEN IN CENTRAL POLAND?

The paper describes the occurrence of an assemblage of Vertigo, composed of four species, Vertigo moulinsiana, V. angustior, V. antivertigo and V. pygmaea, in a small patch of habitat in the degraded environs of Konin, central Poland. The survival of this assemblage in an area strongly affected by human impact has resulted from the microhabitat diversity in the fen and the high quality of the surrounding matrix. Relatively high numbers of V. angustior in the temporarily disturbed part of the fen additionally show that it can inhabit areas subject to occasional and extensive human use. Spatial relations between fen-dwelling species, especially between the most abundant V. moulinsiana and V. angustior, were considered in the context of their preferences for particular habitat conditions relating to the ground moisture levels and microclimate. These seemingly coexisting species were almost completely separated in space, both vertically and horizontally, occupying different meso- and microhabitats.