Sublepidodendron grabaui comb. nov., a lycopsid from the Upper Devonian of China

Abstract

Sublepidodendron wusihense (Sze) Sze and Lepidostrobus grabaui Sze were based on compressions from the upper part of the Wutung Formation (Famennian) of Jiangsu, South China. After studying the morphology and anatomy of abundant well-preserved specimens from two localities, Sublepidodendron wusihense and Lepidostrobus grabaui are reconsidered and viewed as Sublepidodendron grabaui (Sze) comb. nov. This plant is an arborescent, heterosporous lycopsid known from trunk, branches and cones. Leaf bases are spirally arranged, fusiform in outline, with a vascular bundle scar and keel. One specimen is known with a cone attached at the tip of a distal branch. The trunk has an intrastelar parenchyma concentration (pith), exarch primary xylem and secondary xylem. The branch anatomy varies from exarch primary xylem with a small, centrally located pith, to a solid exarch primary xylem strand. Based on the morphology and anatomy of both vegetative and reproductive organs, Sublepidodendron grabaui is placed into Sublepidodendraceae (sensu Kräusel & Weyland, 1949), and Isoëtales (sensu DiMichele & Bateman, 1996).