Zhutheca Liu, Li et Hilton gen. nov., the fertile pinnules of Fascipteris densata Gu et Zhi and their significance in marattialean evolution.
The morphology of the fertile pinnules of Fascipteris densata Gu et Zhi have been subjected to a detailed morphological investigation based on recently collected specimens from the Upper Permian of Yunnan Province, south China. These investigations have revealed that this species possesses synangia of the Asterotheca-type, situated in two or three rows either side of the midrib on a Fascipteris-type pinnule. This arrangement of Asterotheca-type synangia is extremely unusual considering that all other reports of this genus are with a single row of synangia located on each side of the midrib of a pecopteroid-type pinnule. As a consequence of this unique morphological arrangement, a new genus, Zhutheca densata Liu, Li et Hilton gen. et comb. nov. has been created to distinguish this material from other specimens of the Asterotheca and Fascipteris types. The structure and arrangement of the fertile pinnule of Zhutheca are compared with other Palaeozoic and Mesozoic marattialean taxa with which it shares certain features of its morphology. In addition, the stratigraphic, evolutionary and phylogenetic significance of Zhutheca are considered in detail.
Liu
Z
Department of Palaeobotany, Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, People's Republic of China
Li
C
Hilton
J