A new occurrence of Craigia (Malvaceae) from the Miocene of Yunnan and its biogeographic significance

ABSTRACT

The living fossil Craigia consists only two species Craigia yunnanensis W.W. Smith et W.E. Evans and Craigia kwangsiensis H.H. Hsue, endemic to East Asia. Craigia is a typical palaeoendemic genus, with an extensive fossil record in the Northern Hemisphere (North America, Europe and Asia); but there is a temporospatial gap between its fossil occurrences and the modern populations, so its migration history is enigmatic. The earliest fossil record is from Northeast Asia and extant species are relictual, occurring only in southwestern China, northeastern India and northern Vietnam. Here, we describe a new fossil species, Craigia lincangensis Wang et Xie sp. nov., based on fruits from Late Miocene of Yunnan, China. This new finding along with other fossil records in Asia clarifies the southward migration route in Asia. The Miocene occurrence in this investigation represents the youngest record of Craigia so far in Asia and sheds new light on the final migration into its relict habitat.

KEYWORDS:

• Biogeography
• Craigia
• Late Miocene
• Lincang
• Malvaceae
• Yunnan

Acknowledgments

We sincerely appreciate Prof. Cheng Quan and another anonymous reviewer for carefully reviewing the manuscript and made helpful comments and suggestions. We also thank Prof. Steven R. Manchester for the valuable suggestions in fossil identification, as well as providing the extant photos of Craigia. We are grateful to Dr Bai-Nian Sun, Dr De-Fei Yan, Dr Jing-Yu Wu, Dr Bao-Xia Du, Dr Tao Yang and Dr Jun-Ling Dong for the constructive comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) [No. 2019QZKK0704]; the Strategic Priority Research Program (B) of the Chinese Academy of Sciences [No. XDB26000000]; the Foundation of the State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS (No. 173126) and National Natural Science Foundation of China [Nos. 41972008 and 31870200].