State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
Research Center of Palaeontology & Stratigraphy, and MOE Key-Lab for Evolution of Past Life and Environment in Northeast Asia, Jilin University, Changchun, 130026, China.
Sci Rep. 2017 Jun 21;7(1):4009. doi: 10.1038/s41598-017-04349-6.
The genus Schima includes about 20 species and is distributed only in southern China and adjacent areas of Asia. The previous molecular phylogenetic analysis suggested Schima is in the tribe Gordoniae, along with Gordonia and Franklinia. However, because few fossils have been reported, the biogeographic origin of Schima is still poorly known. In this paper mummified fossil fruits of Schima are described from the upper Oligocene Yongning Formation of the Nanning Basin, Guangxi, South China. In gross morphology, the new fossil species, Schima kwangsiensis, is similar to the extant S. superba by its pentacarpellate, loculicidally dehiscent capsules, 5 imbricate sepals, pedicels with bracteoles and marginally winged seeds. Due to its excellent preservation, the new species may provide sufficient details for understanding the early evolutionary and phytogeographic history of the genus. Morphological clustering analysis shows that the new fossil species is closely related to two extant species (S. wallichii and S. superba) in the genus, implying that they may belong to an ancient taxon that occurs earlier than the others. More importantly, this discovery represents the earliest record of this genus in Asia and it explicitly moves the fossil record back to the late Oligocene in this region.
木莲属约有 20 种，仅分布于中国南方和亚洲相邻地区。先前的分子系统发育分析表明，木莲属与 Gordonia 和 Franklinia 一起位于 Gordoniae 族中。然而，由于报道的化石很少，木莲属的生物地理起源仍然知之甚少。本文描述了来自中国广西南宁盆地晚渐新世永宁海相地层的木莲属木乃伊化果实化石。在宏观形态上，新的化石种，广西木莲，与现存的木莲属 S. superba 相似，其聚合心皮、室背开裂的蒴果，5 枚覆瓦状排列的萼片，具小苞片的花梗和具边缘翅的种子。由于其保存完好，该新种可能为理解该属的早期进化和植物地理历史提供了足够的细节。形态聚类分析表明，该新化石种与该属中的两个现存种（S. wallichii 和 S. superba）密切相关，这表明它们可能属于一个比其他种更早出现的古老类群。更重要的是，这一发现代表了该属在亚洲的最早记录，明确将化石记录追溯到该地区晚渐新世。
