Bryum marratii Hook. & Wilson (Bryaceae, Musci) reported new to China

Bryum marratii Hook. & Wilson is reported new to China. The species is distinguished by the following characters: plants bright green, leaves strongly concave, apex obtuse, margins plane, border lacking, costae ending well below apex; pyriform capsule with rostellate lid. In China, the newly recorded species is mainly distributed in the southwestern Ngari region, occasionally in Shigatse of Tibet, mostly in soil banks of alpine or seasonal water bodies. The B. marratii populations in China differ from those in other areas by smaller plant size, shorter setae, and smaller leaves and leaf cells. The principal distinctive characters that separate B. marratii from similar species within the genus Bryum are discussed. Given the small population size and habitat fragmentation, B. marratii should be classified as a threatened species in China.