A new gigantopterid taxon Paragigantopteris qingloongensis gen. et sp. nov. from the Permian (Wuchiapingian) of southwestern China: Taxonomic and biogeographic implications

Abstract

Since gigantopterids are an enigmatic group of plants as they are grouped by their megaphyllous leaves with distinctive reticulate venation, their systematic relationships between each other are also so far essentially unknown. Clarifying these confusions about gigantopterids requires new information provided by more detailed studies of previously described and/or new material. Variations in venation can provide clues to explore the taxonomic relationships and diversity of gigantopterid taxa, even leading to an improved understanding of their biogeography. Recently, a gigantopterid-bearing plant assemblage was discovered from the Wuchiapingian Lungtan Formation of Qinglong County, Guizhou, China; some of which having the diagnostic venation pattern of gigantopterids are recognized here as Paragigantopteris qingloongensis gen. et sp. nov. The new genus has basal actinodromous venation with three primary veins radiating from the petiolar insertion and double meshes formed by the tertiary and occasionally quaternary veins, distinctly different from other double-meshed gigantopterid genera. P. qingloongensis gen. et sp. nov. is characterized by its obovate, entire margined, simple leaves. Together with previous studies, the taxonomic and biogeographic implications of Paragigantopteris gen. nov. are discussed. Since the new genus is characterized by megaphyllous leaves with angiosperm-like reticulate venation while lacking sutural veins, it conforms to the more restricted concept proposed by Glasspool et al. (2004a). Besides, the occurrence of Paragigantopteris gen. nov. known from a single deposit and its absence elsewhere may indicate that it was an endemic, rare taxon.