Oxyrrhynchium hians (Brachytheciaceae, Bryophyta) includes several morphologically distinct and cryptic species in northwestern Europe

A study of the variable species Oxyrrhynchium hians s.l. in NW Europe based on nuclear ITS, and plastid rpl16 and trnLtrnF, as well as morphology, revealed unsuspected species level diversity. Three taxa are distinguishable by morphology: O. distichum with complanate or sub-complanate branch leaves and long and narrow leaf lamina cells, O. hians with cordate or broadly ovate, concave leaves that are evenly arranged around the stems and branches, and O. swartzii with mostly complanate or sub-complanate branch leaves and compared with O. distichum relatively short and wide leaf lamina cells. In Sweden O. distichum grows almost exclusively on base-rich or calcareous rocks and has been recorded from a belt stretching from the Baltic Sea islands of Öland and Gotland to Dalarna and southernmost Norway, whereas the other two species grow on various substrates and have wider distributions. Oxyrrhynchium hians grows in more nutrient-rich habitats than O. swartzii and is therefore absent from regions with relatively poor soils. Oxyrrhynchium swartzii occurs northwards to Sør-Trøndelag in Norway and Jämtland and Medelpad in Sweden and includes two semi-cryptic species that differ slightly in size and may have relatively more western and eastern distributions, respectively, in Fennoscandia.