Rare and new bryophytes (Bryophyta, Marchantiophyta) for the Leningrad Region on outcrops of Devonian sandstones in the Luga River Basin (European Russia)

Outcrops of Devonian sandstones in the Leningrad Region represent a unique habitat for bryophytes. These outcrops are locally different in chemical composition, light and moisture conditions and serve as specific microhabitats for different bryophyte species and their communities. In this article, four rare liverwort and 12 rare moss species are reported from the outcrops of Devonian sandstones in the Luga River Basin which covers the southwestern part of the region. Description of habitats and distribution of each species are discussed. Mesoptychia collaris is new for the Leningrad Region. This specimen is described and illustrated by detailed photomicrographs. The discovery of M. collaris in the Leningrad Region is the southernmost in Northwestern Russia. Among the other rare species, Tortula lingulata is protected in Russia, Atrichum flavisetum, Mesoptychia heterocolpos, Metzgeria furcata, Mnium hornum, Myurella julacea, Saelania glaucescens are protected in the Leningrad Region. An analysis of species composition and distribution of bryophytes persuades us to distinguish the outcrops of Devonian sandstones in the Luga River Basin as important bryophyte refuges of the northwestern outskirts of the Russian Plain.