Introduction. Following on from work on the European bryophyte Red List, the taxonomically and nomenclaturally updated spreadsheets used for that project have been expanded into a new checklist for the bryophytes of Europe. Methods. A steering group of ten European bryologists was convened, and over the course of a year, the spreadsheets were compared with previous European checklists, and all changes noted. Recent literature was searched extensively. A taxonomic system was agreed, and the advice and expertise of many European bryologists sought. Key results. A new European checklist of bryophytes, comprising hornworts, liverworts and mosses, is presented. Fifteen new combinations are proposed. Conclusions. This checklist provides a snapshot of the current European bryophyte flora in 2019. It will already be out-of-date on publication, and further research, particularly molecular work, can be expected to result in many more changes over the next few years.

Hymenostylium xerophilum is described as a new species from the European Alps. Molecular rps4 and ITS data support its recognition and elucidate its affinities to other species of the tribe Pleuroweisieae. It is closely related to H. gracillimum, comb. nov., which is based on the old and neglected Gymnostomum gracillimum, which replaces the recent name G. boreale. Both species share non-coloured to pale yellowish-brown rhizoids, stem central strand and indistinct sclerodermis, keeled leaves, and concave laminae in abaxial view. They differ from each other in leaf shape and several essentially quantitative characters. Sporophytes have never been found in H. xerophilum, but they are known from several localities in H. gracillimum. The former colonizes rather dry, sunny to half-shaded calcareous rocks, whereas the latter needs moist and shaded rock habitats and shows a preference for subneutral slate. At present, H. xerophilum is known only from the Alps (Austria, and a single site in Germany), where it is rather widespread in calcareous regions. H. gracillimum seems to be a distinctly rarer plant, to date known only from eight Austrian sites and one locality in Russian Karelia. Other published records under the name G. boreale have been wrongly attributed to this species. Lectotypes are designated for G. gracillimum and Gyroweisia acutifolia. A key to Hymenostylium and the genera of Pleuroweisieae in Europe is presented. Thicker rhizoids of both species are covered with a thick, non-coloured protective layer and filled with oildroplets and leucoplasts. They represent a subterranean secondary protonema, which plays an important role in the survival and propagation of these mosses, vital especially in the case of the non-sporulating H. xerophilum.

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