Cyathodium Kunze (Cyathodiaceae: Marchantiales), a tropical liverwort genus and family new to Europe, in Southern Italy

Abstract

The tropical liverwort Cyathodium, and the family Cyathodiaceae are reported, as new to Europe, growing beneath a deeply shaded dripping recess in the Valle delle Ferriere, a limestone valley near Amalfi, on the Sorrento Peninsula, Southern Italy. The Italian specimens closely match C. foetidissimum Schiffn. from the tropics, but internal cells in the air chambers and crystals in epidermal cells are noted for the first time in the genus. As assumed for a population of the tropical fern Woodwardia radicans (L.) Sm. living in the same area, the Italian population of Cyathodium is most probably a pre-glacial relic rather than a recent arrival from sub-Saharan Africa. Thallus structure in Cyathodium is compared with that of two other deep-shade marchantialean liverworts, Dumortiera and Monoclea, which also exhibit structural adaptation to maximize interception of low irradiances. As in the protonemata of Schistostega, the green luminescence in Cyathodium results from light reflection and is probably a mechanism enhancing light interception.