Reinvestigation of the Late Devonian Lycopsid Sublepidodendron grabaui from Anhui Province, South China.

Abstract

Simple SummaryThe lycopsid Sublepidodendron is cosmopolitan in the Late Devonian and Early Carboniferous. Sublepidodendron grabaui is known from several localities of the Upper Devonian Wutong Formation in South China, with its overall morphology and male reproductive organs (i.e., the microsporangiate strobili and microspores) studied previously. Here we describe new specimens of S. grabaui from Guangde City, Anhui Province, to get further knowledge on this plant, especially its female reproductive organs (i.e., megasporangiate strobili and megaspores). The megasporangiate strobili are borne terminally on fertile axes and occasionally dichotomized, bearing at least eight Lagenicula-type megaspores with a small gula in each sporangium. Based on the previous and present study, this plant is considered as a tree lycopsid exhibiting multiple dichotomized stems, occasionally produced lateral branches and monosporangiate strobili.South China displays Devonian strata with well-exposed outcrops and is regarded as a diversity hotspot of Late Devonian lycopsids. The heterosporous lycopsid Sublepidodendron grabaui has been studied for over ten years, with its general morphology, aerial stem anatomy, microsporangiate strobili, and growth architecture reported. Based on new specimens from Guangde City, Anhui Province, this study provides further knowledge about the megasporangiate strobili and megaspores of S. grabaui. Its slender megasporangiate strobili occur singly or in pairs and occasionally bifurcate in the middle-upper portion. Each megasporophyll consists of a flattened pedicel and an adaxially curved lamina. The lamina forms a downturned heel at the base. Each sessile megasporangium contains at least eight Lagenicula-type megaspores with a small gula. The other observed characteristics of S. grabaui in this study conform to those previously known and are compared to relative coeval taxa.