A taxonomic revision of Oligotrichum Lam. & DC. (Polytrichaceae) in the Sino-Himalaya

Abstract

A taxonomic revision of the moss genus Oligotrichum Lam. & DC. (Polytrichaceae) is provided for the Sino-Himalayan region. This area includes the Himalaya and the Hengduan Mountains of south-western China (Yunnan, Sichuan, and Xizang [Tibet] Provinces). Field work in recent decades has resulted in much new material for taxonomic revision. Light microscopy was used to distinguish seven species from the study area: O. aligerum Mitt., O. crossidioides P.C.Chen & T.L.Wan ex W.X.Xu & R.L.Xiong, O. falcatum Steere, O. falcifolium (Griff.) G.L.Sm., O. nepalense G.L.Sm., O. obtusatum Broth., and O. semilamellatum (Hook.f.) Mitt. Two species are excluded: O. hercynicum (Hedw.) Lam. & DC., as no specimens of this European and North American species have yet been found from the Sino-Himalayan region, and O. glaciale C.C.Towns., which has been transferred to a recently established genus Delongia N.E.Bell, Kariyawasam, Hedd. & Hyvönen, described elsewhere. The material now available has facilitated new observations on important characters such as the structures of the leaf lamellae and sporophytes. A key to accepted species is provided, as well as descriptions, synonymy, typification, line drawings, an ecological summary, and biogeographical information including distribution maps for all species. Oligotrichum falcatum is reported as new to India and Nepal, and O. obtusatum new to India and the Sichuan Province of China. Two varieties (O. semilamellatum var. darjeelingense Gangulee and var. edentatum Gangulee) are newly synonymised with O. semilamellatum. Finally, some observations on the regional ecology and phytogeography of the species are made and a list of specimens studied is appended.

Keywords:

• Oligotrichum
• Polytrichaceae
• Sino-Himalaya
• Taxonomy

Acknowledgements

The Royal Botanic Garden Edinburgh is thanked for providing facilities for the MSc course in Biodiversity and Taxonomy of Plants under which this project was undertaken, and the University of Edinburgh for providing the studentship. The Royal Botanic Garden Edinburgh is supported by the Scottish Government's Rural and Environment Science and Analytical Services Division. During 2018, we are also grateful for the support of players of People's Postcode Lottery towards our scientific research. The first author gratefully acknowledges the Commonwealth Scholarship Commission, UK, and the School of Biological Sciences, the University of Edinburgh, for providing the funding and the financial support to complete the project. The authors wish to thank the curators of the herbaria BM, E, HKUN, NICH, NY, and PE for loans of types and other herbarium specimens. Dr Terry Hedderson (University of Capetown), Dr Jaakko Hyvönen (University of Helsinki) and 2 anonymous reviewers are thanked for their comments and advice.

Taxonomic Additions and Changes:

Oligotrichum semilamellatum (Hook.f.) Mitt. (Oligotrichum semilamellatum var. darjeelingense Gangulee syn. nov., Oligotrichum semilamellatum var. edentatum Gangulee syn. nov.)

ORCID

Neil E. Bell http://orcid.org/0000-0002-2401-2968