A new naturalized alien plant in Sicily: Cotula australis (Sieber ex Spreng.) Hook. f. (Asteraceae) on the Acropolis of Lipari Island (Aeolian Archipelago)

In February 2018 a copious population of Cotula australis Hook f. (Asteraceae, Anthemideae) was found on the cobblestones of the Acropolis of Lipari Island (Aeolian Archipelago, NE Sicily). This population represents the first record in southern Italy and is located at a distance of about 470 km as the crow flies from the nearest neighbour. From the phytosociological point of view, C. aus- tralis dominates a therophytic subnitrophilous dwarf vegetation of trampled sites which can be ascribed to the cosmopolitan class Polygono-Poetea annuae Rivas Mart. 1975. This plant communi- ty is proposed as a new association, Galio muralis-Cotuletum australis, which can be considered a Mediterranean vicariant of the Polycarpo tetraphylli-Cotuletum australis Wildpret, Perez de Paz, Del Arco & Garcia Gallo 1988, recorded from the Canary Islands and Portugal. Some hypotheses on the origin of the Aeolian population in the frame of a documented very fast recent propagation world- wide are discussed.