THE GENUS SHUICHENGELLA GEN-NOV AND SYSTEMATIC CLASSIFICATION OF THE ORDER OSMUNDALES

Recently two permineralized osmundaceous stems were discovered, completely embedded in the matrix of Upper Permian coal balls from the Wangjazhai mine of the Shuicheng district, Guizhou Province, China. These specimens, together with previous ones, provide a basis for describing the genus Shuichengella gen. comb. nov., of which the type species is Shuichengella primitiva (Li) comb. nov. This taxon is the structurally preserved stem of osmundalean plants, which possesses an ectophloic dictyoxylic siphonostele with mixed pith and a heterogeneous cortex without the mantle of leaf-bases and/or adventitious roots and sclerenchymatic sheaths of leaf traces. The root-traces departed simply from the leaf-traces with 3 groups of protoxylem in the cortex. Based on anatomical studies, it is proposed that the Order Osmundales should contain one family Osmundaceae with four subfamilies: Thamnopteroideae, Osmundoideae, Shuichengelloideae and Guaireoideae.