New Sphenophyllum plant from the Upper Devonian of Zhejiang Province, China

Abstract

Sphenophyllum was an important and long-surviving sphenopsid genus in the Paleozoic floras, with a worldwide distribution. A new species, Sphenophyllum changxingense sp. nov., is described from the Upper Devonian Wutong Formation of Changxing County, Zhejiang Province, China. This plant is characterized by two orders of slender axes and wedge-shaped leaves borne in whorls. The axes bear short spines and show longitudinal ridges and furrows on surface. Three to eight isophyllous leaves, with one, two, or no second-order axes, are attached at each node of first-order axes. Leaves bear spines and show a bilobate morphology; the two leaf lobes divide distally to form several marginal segments, each segment with a leaf vein. Sphenophyllum changxingense represents an early and primitive species within the genus, in light of the absence of heterophylly and specialized hook-like leaves. Like some Carboniferous and Permian species, it appears to have formed dense mats with mutually supportive axes. This plant adds to the known diversity of early sphenopsids in the Late Devonian.

Keywords:

• Sphenophyllum
• sphenopsid
• leaf morphology
• Wutong Formation
• Devonian
• fossil plant

Acknowledgements

The authors thank Mr Qi Dunlun (Anhui Geological Survey) and Dr Meng Meicen (China Science Publishing & Media Ltd) for their assistance in field work and Dr Xiong Conghui (Lanzhou University) for providing important literature about Sphenophyllum.