中国科学院南京地质古生物研究所机构知识库

The early land plant group Zosterophyllopsida has a wide distribution in the global Silurian to Devonian floras and the morphological study of this group is fundamentally significant to plant evolution. Demersatheca contigua is an endemic zosterophyllopsid of the Early Devonian flora in South China. Here its morphology is studied based on re-examination of the specimens previously attributed to Zosterophyllum contiguum and Z. australianum from the Posongchong Formation of Yunnan and the observations on newly collected specimens from the Cangwu Formation of Guangxi Zhuang Autonomous Region, southwest China. The strobilus of D. contigua consists of four rows of lateral sporangia decussately arranged biconvex sporangia with marginal dehiscence bending towards the strobilus axis to make the strobilus a cylindrical-shape. The structure of the D. contigua strobilus is reconstructed and the diagnosis of the plant is emended in the aspect of four-row decussate sporangium arrangement. The nomenclature of D. contigua is summarized and the lectotype of the species is formally proposed. Demersatheca contigua is a shared plant member of Yunnan and Guangxi Early Devonian flora of southern China and its paleophytogeographic implication to southern China Early Devonian is discussed. (C) 2020 Elsevier B.V. All rights reserved.