Riccia atromarginata (Ricciaceae, Marchantiophyta) new to the west Balkan peninsula

This is the first record of the liverwort Riccia atromarginata on the west Balkan Peninsula. It was found on conglomerate terraces in Podgorica, Montenegro, at the confluence of Ribnica and Moraca River. The material from Montenegro as well as living samples from Tenerife, Gran Canaria and Cyprus serve as a basis of a detailed description of the species on which to Riccia atromarginata can be reliably identified. However, there is a distinct variability of some characteristics.