The moss Jaffueliobryum wrightii (Sull.) Thér.var.rhombicum X.L.Bai & Sarula is described as a new variant species based on a collection from shady slopes in loess hilly regions,Qingshuihe County,Inner Mongolia.It is distinguished from Jaffueliobryum wrightii (Sull.) Thér.by some significant characteristics.J.wrightii var.rhombicum appeared that upper laminal cells rhomboidal and dorsally strongly thick-walled,marginal cells not differentiated,cells of costal transverse section are not differentiated,non bulging ventral epidermis cells,lamina 0.7—0.8 mm in length,awn 0.8—1.3 mm in length.Characteristic descriptions and geographic distribution map of the two species are provided.Moreover,an identification key for the species recognized in Jaffueliobryum is also provided.