华南晚泥盆世—早石炭世楔叶类植物的系统发育及叶形态演化研究

Sphenophytes, a plant group originated since the Late Devonian or even earlier, constituted one of the dominant groups in Carboniferous and Permian swamp forests and contributed to the formation of the Late Paleozoic floras. Based on abundant fossil materials from South China, this project aims to study Late Devonian and Early Carboniferous sphenophytes found in this area, to reveal their morphological and anatomical features by using comprehensive methods, to recognize some potentially new plants, to re-investigate the previously known species, and to provide whole-plant reconstructions of some selected species. Based on new biological features obtained and an updated synthesis of the characters of early sphenophytes and other related taxa, this project aims, by reconstructing a phylogenetic tree, to study the inter-relationships among known sphenophytes and their position in the “Tree of Life” of euphyllophytes. Additionally, we will focus on leaves of sphenophytes, which have a rich fossil record in the Late Devonian and Early Carboniferous strata, to measure leaf morphological parameters and to study the trend and rate of leaf morphologies within early sphenophyte plants.

楔叶类植物起源于晚泥盆世或更早时期，是石炭、二叠纪沼泽森林的优势类群之一，同时也是晚古生代全球植物区系形成的贡献者之一。本项目拟以华南丰富的化石材料为基础，研究该地区晚泥盆世至早石炭世这一时段的楔叶类植物，通过多种手段揭示形态学、解剖学信息，建立可能的新属种，对已有属种进行重新认识，复原整体植物。基于获得的新的生物学特征，对早期楔叶类植物及相关类群进行性状分析，运用分支系统学方法重建系统发育树，研究楔叶类植物内部类群的亲缘关系及楔叶类在真叶植物“生命之树”的位置。基于晚泥盆世—早石炭世丰富多样的楔叶类植物叶片化石，项目拟统计叶形态特征参数，揭示早期楔叶类植物的叶形态演化趋势和速率。

楔叶类植物最早起源于泥盆纪，至石炭、二叠纪其属种多样性达到最大，并构成全球沼泽森林的优势类群，是形成晚古生代植物地理大区的贡献者之一。本项目立足于长江下游五通组中的化石材料，报道并描述了楔叶属新种——范湾楔叶（Sphenophyllum fanwanense），梳理了华南晚泥盆世楔叶属的名实和分布，提出泥盆纪楔叶属（乃至楔叶类植物）无异叶性，这一习性的起源可能与森林的复杂化有着密切的联系。通过新的材料揭示了Xihuphyllum megafolia的解剖结构，该植物具有初生木质部和皮层，无次生木质部结构。对楔叶类植物Eviostachya hoegii和Hamatophyton verticillatum的形态特征提出一些新的认识。建立并描述了五通组中一新属种Qianshouia mira，丰富了晚泥盆世期间维管植物叶形态的多样性。发现内蒙古苏尼特左旗的上泥盆统及其中赋存的一个包括楔叶类、古羊齿、原始真蕨类Melvillipteris sonidia等多门类的植物群。这些研究进一步表明华南在晚泥盆世至石炭纪早期是楔叶类植物演化和辐射的中心。