Female plants and range extensions in Scapania davidii Potemkin (Scapaniaceae, Marchantiophyta)

Scapania davidii Potemkin, previously known from the Xizang district of China, East Nepal and India (West District of Sikkim), is now reported from Bhutan and the North and East Districts of Sikkim and Anjaw District of Arunachal Pradesh in India. Female plants with well-developed perianths are described and illustrated here for the first time. The differentiation of S. davidii from S. ornithopoides (With.) Waddel is discussed. The distinguishing features of S. davidii are hemispherically convex, broadly oval to nearly reniform leaf lobes, the subequal size of the dorsal and ventral lobes resulting in the formation of very compact head-like shoot apices, the decurrency of the dorsal lobe, contrasting deep brown pigmentation of marginal teeth, formation of variable paraphyses in the axils of vegetative leaves and the male and female bracts, and the morphology of the perianth with 1–2-celled cilia on its inner surface closer to the perianth-mouth. An expanded description, illustrations and map showing the s...