Contribution to the knowledge of Mediterranean wetland vegetation: Lemnetea and Potamogetonetea classes in Western Sicily

The freshwater aquatic vegetation of the Lemnetea and Potamogetonetea classes in Western Sicily was surveyed and analyzed. 85 lakes and small pools were investigated collecting 147 phytosociological unpublished relevés to integrate the very scarce available data (only 3 relevés). By applying statistical analyses on abundances data and on the bases of physiognomy and dominant species, two alliances (Lemnion minoris and Stratiotion) and four different coenoses have been identify for the Lemnetea class; while 11 associations, assigned to two orders (Potamogetonetalia pectinati and Callitricho hamulatae-Ranunculetalia aquatilis) and four alliances (Potamogetonion, Nymphaeion albae, Ranunculion aquatilis and Ranunculion omiophyllo-hederacei) have been recognized for the Potamogetonetea class. A new association (Junco bufonii-Ranunculetum omiophylli ass. nov.) and a new subassociation (Ranunculetum peltati ranunculetosum rionii subass. nov.) have been proposed, whereas other six vegetation units were found to be new for the study area (Potamogetono-Ceratophylletum submersi, Potamogetonetum pusilli, Ranunculetum aquatilis, Ranunculetum peltati and Ranunculetum rionii, Lemno-Callitrichetum obtusangulae). For all the coenoses recognized, new insights on the floristic composition, syntaxonomy, synphiognomy, synecology and synchorology are reported, offering a reasoned overview of the aquatic vegetation of the western sector of the main Mediterranean island.