A new species of Meliolinites associated with Buxus leaves from the Oligocene of Guangxi, southern China

Abstract

A new species of Meliolinites (fossil Meliolaceae), M. buxi sp. nov., is reported from the Oligocene Ningming Formation of Guangxi, South China. The fungus has hyphopodia characteristics of extant Meliolaceae, such as thick-walled, branching hyphae with appressoria and phialides. However, these fossils entirely lack mycelial or perithecial setae and have only a few phialides, thereby distinguishing the new species from most known species. The fungus was discovered on the adaxial and abaxial cuticles of several fossilized Buxus leaves. Thickening and twisting of cell walls in the Buxus leaf cuticle, along with the parasitic feeding strategy of the extant Meliolaceae, suggest that a parasitic interaction between Buxus and M. buxi seems feasible. The distribution of modern Meliolaceae suggests that they live in warm, humid subtropical-tropical climates. It is possible that the presence of M. buxi indicates a similar climatic condition. The co-occurrence of large-leaf Buxus and floristic comparisons of the Ningming assemblage also corroborate this conclusion.

• Buxaceae
• fossil Meliolaceae
• palaeoecology
• parasitism

Acknowledgments

We thank Executive Editor Dr Seifert, Associate Editor Conrad Schoch and two anonymous reviewers for their invaluable suggestions and thoughtful comments for improving the manuscript. We also thank Ru-Yong Zheng from the State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, for her advice on the paper. We also thank David L. Dilcher from the Departments of Geology and Biology, Indiana University, and Subir Bera from the Centre of Advanced Studies, Department of Botany, University of Calcutta, for their kindness in providing scientific literature on fossil Meliolaceae. This work is supported by the National Basic Research Program of China (973 program number 2012CB822003), the National Natural Science Foundation of China (Grants 41172022, 41272026) and the Fundamental Research Funds for the Central Universities (No. lzujbky-2014-285).