A new moss species from northwestern China: Bryum glacierum (Bryaceae)

Abstract

The form of the gemmae appears to be constant within Bryum species, and it is an important character for distinguishing among closely related species. In this study, we describe a new species of Bryum, B. glacierum Y.Y. Liu & Y.H. Wu, that was collected from Tianshan Mountain in China along with a description of its gemmae. This species is distinguished morphologically by (1) gemmiforfm to julaceous shoots; (2) broadly ovate leaves, strongly concave, with obtuse to acuminate apex, plane and undifferentiated leaf margins, rhombic to rhomboidal distal and medial cells; and (3) dark red-brown, obconic or ovate bulbils with peg-like leaf primordia, densely clustered in the leaf axils of sterile shoots. The new moss species is currently known from two localities in northwestern China. The species seems to prefer high altitudes, growing as a pioneer mainly on ground exposed by retreating glaciers. The principal distinctive characters that separate Bryum glacierum from similar species of Bryum and Pohlia are discussed. An identification key for bulbiferous species of Bryum in China is provided.