云南景谷早中新世翅子树属叶片化石的发现及其古生态和植物地理学意义

锦葵科(Malvaceae Juss.)翅子树属(Pterospermum Schreb.)主要分布于热带亚洲，该属化石目前只在印度有少量记录。本研究报道了产自云南省景谷县(23°31′N，100°42′E)下中新统三号沟组的翅子树属叶片化石。通过形态学研究鉴定出3个种：双兴翅子树(P.shuangxingii Y.S.Zhao, J.Huang et T. Su sp. nov.)，叶片偏小型，顶端截形并具3浅裂，与现今分布于东南亚地区的大花翅子树(P.grandiflorum Craib)形态较为相似；云南翅子树近似种(P.cf.yunnanense H.H.Hsue)，叶片偏小型，顶端不分裂；翅子树属一未定种(Pterospermum sp.)，叶片中型，叶片顶端具齿。景谷县翅子树属化石的发现证明，早中新世该属就在我国西南地区分化并繁盛至今。综合本研究以及已有证据，翅子树属可能从印度次大陆起源，随后向亚洲东部和东南部的热带地区扩散，最终形成了现今热带亚洲的分布格局。此外，本研究还描述了翅子树属化石叶片上的9种昆虫取食类型，与该属现生种叶片的昆虫取食形态一致，表明该属现今的植食性昆虫取食行为可能在早中新世就已经出现。

Fossil leave of Pterospermum (Malvaceae) from the Early Miocene of Jinggu,Yunnan Province with its paleoecological and phytogeographical implications

Pterospermum Schreb.(Malvaceae Juss.)is mainly distributed in tropical regions of Asia and only has a few fossil records in India. This study reported fossil leaves of Pterospermum from the Lower Miocene Sanhaogou Formation in the Jinggu basin(23°31′N, 100°42′E), Yunnan Province, China. The Jinggu basin is a Cenozoic coal and oil-bearing basin with Sanhaogou Formation in the lower part and Huihuan Formation in the upper part. Three Pterospermum species were classified based on the detailed morphological comparison with both fossil and living species, i.e., P. shuangxingii Y. S. Zhao, J. Huang et T. Su sp. nov., P. cf. yunnanense H. H. Hsue, and P. sp. P. shuangxingii sp. nov. is characterized by obovate leaf shape, untoothed margin, trilobed on the top of the leaf, cordate and asymmetrical leaf base, which is similar to the living species P.grandiflorum Craib from Southeast Asia. P. cf. yunnanense H. H. Hsue is represented by unlobed leaf with relatively small leaf size, and P. sp. has two simple tooth at the top of leaf blade. The discovery of Pterospermum from the Jinggu basin indicates an Early Miocene diversification of this genus in southwestern China. Together with previous molecular analyses and fossil records, we proposed that Pterospermum may originate by the Early Eocene in India and disperse to Southeast Asia during the Neogene. Besides, this study observed quite similar insect damage patterns on both fossil and modern Pterospermun leaves, among them, some were caused by weevil(Brachyceridae: Desmidophorus). It suggests that the modern plant-insect interaction in this genus could be dated back to the Early Miocene.