A new fossil species of Meliolinites Selkirk associated with Rhodoleia leaves from the Upper Pliocene of southwestern China

ABSTRACT

Fossil epifoliar fungi are valuable indicators of paleoenvironment and paleoecology. The Meliolaceae, members of which typically inhabit the surface of living plants as biotrophs or pathogens, is one of the largest groups of epifoliar fungi. In this study, we report a novel fossil species of Meliolinites Selkirk (fossil Meliolaceae), Meliolinites tengchongensis, on the lower epidermis of compressed fossil Rhodoleia (Hamamelidaceae) leaves from the Upper Pliocene Mangbang Formation of Tengchong, Yunnan, southwestern China. Meliolinites tengchongensis is characterized by web-like, superficial, brown to dark brown, septate, and branching mycelia bearing 2-celled appressoria and unicellular phialides. The fungal colonies also include ellipsoidal, 5-celled, 4-septate ascospores and dark brown perithecia with suborbicular outline and verrucose surface. The well-preserved vegetative and reproductive organs help us to explore the potential disease process of the new fossil species. Besides, the presence of fungal remains indicates that the fungal taxon might have maintained its host preference since at least the Late Pliocene. Furthermore, the occurrence of both fossil fungi and their host plants in Tengchong indicate a subtropical–tropical, warm, and humid climate during the Late Pliocene, whereas the distribution pattern of the fungi on the host leaves suggests that Rhodoleia may have been a part of the middle–upper canopies in the Tengchong Late Pliocene multilayered forest.

KEYWORDS:

• Epifoliar fungi
• late pliocene
• meliolaceae
• paleoclimate
• paleoecology
• 1 new taxon

ACKNOWLEDGMENTS

We would like to thank the two anonymous reviewers who have significantly contributed to improving the present work.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00275514.2024.2348980.

Additional information

Funding

This work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program [grant 2019QZKK0704], the National Natural Science Foundation of China [grants 31870200, 32170222, and 42272002], and the Natural Science Foundation of Gansu Province, China [grant 22JR5RA438].