Addenda to the lichen flora of the Ticino river valley (western Po Plain, Italy)

The Ticino river valley is a focal area for biodiversity in the western Po Plain (Northern Italy). Lichens have been collected by the author from 91 sites in the period 2011-2017. These collections and the few literature data published in the last decade have been summarized. Twenty-eight species (15 terricolous, 5 epiphytic, 3 lignicolous, 3 saxicolous, 1 epiphytic and lignicolous, 1 terricolous and epiphytic), mostly belonging to genus Cladonia, are reported here as addenda to the floristic list published 15 years ago by the Lombardy Ticino Park, which included 123 species. Many of the newly recorded species are interesting under a conservation or biogeographical standpoint.