1. Department of Ecology and Evolutionary Biology; University of Connecticut; 75 North Eagleville Road Storrs Connecticut 06269-3043 USA
2. Department of Botany; Faculty of Science; University of South Bohemia; Ceske Budejovice 37005 Czech Republic
3. Institute of Parasitology; Biology Centre AS CR; Ceske Budejovice 37005 Czech Republic
4. Dipartimento di Scienze della Vita e dell'Ambiente; Università Politecnica delle Marche; Via Brecce Bianche Ancona 60131 Italy