叉蕨属（叉蕨科）的范畴及中国叉蕨属的分类学修订

The genus Tectaria, mainly in tropics, is one of the most derived groups within ferns. Nothing is more remarkable to Tectaria than its hyperdiverse morphology, with dramatic number of species. The circumscription of Tectaria, however, is long in dispute, and recently, more disagreements arose on its systematic concept. On the other hand, many problems remain to the taxonomy of Tectaria in China. For example, Tectaria is too narrowly applied in China; some tectarioid species are pending to be assigned an appropriate genus; some species reported to be endemics need to be critically reviewed in identification; several complex of species are to be resolved as distinguishable entities; the nomenclature and geographical distribution of some species in China are in confusion due to lacking comparison with those in neighbouring areas, and so on. .Aiming to the problems mentioned above, we are planning to conduct a series research in next four years. The planning works include morphological observations on populations in wild, a comparison of herbarium collections between China and neighbouring areas, examining spores in size and in shape, examining chromosome numbers, and sequencing three plastids (rbcL, atpB, and trnL-F) for all Chinese species, as well as for some key species outside China. When obtaining all these data, we will clarify the variation pattern of morphological characters and evaluate their significance in taxonomy and systematics. Then we could demonstrate the species concept of Tectaria and reveal relationships between species. Thus our goal of this project, the revision of Tectaria's circumscription and revision of Chinese Tectaria, will be achieved..Obviously, the planning project is meaningful on several aspects. First, we will demonstrate the concept of Tectaria which has been argued for many years, and produce a solid scheme for the systematics of Tectaria and for that of Tectariaceae. Second, we will reveal hybridizations in Chinese Tectaria and surely add knowledge on the role of hybridization on the evolution of Tectaria. Third, our research will benefit for the progressive revision of Fern Flora of China, and benefit for the understanding, as well as conservation, of the diversity of tropical ferns in China.

叉蕨属是系统演化水平最高的蕨类类群之一，热带分布，属内形态分化极其多样；因为形态多样，叉蕨属的分类学范畴一直争论不断。另一方面，中国叉蕨属的分类学问题还很突出：属的概念过于狭窄，部分种的归属待定；很多特有种的真实身份存疑，复合群的物种难辨；地区间的标本缺乏比较，种的命名与分布资料混乱。我们拟开展形态、孢粉、细胞与分子序列资料的采集与评价工作，结合孢粉、细胞与分子资料，阐明形态性状的变异式样与系统学意义；把形态变异与物种生物学资料相关联，阐明中国叉蕨属的物种概念和复合群的划分；通过详细的野外调查和地区间的标本比较，解决种的命名和地理分布混乱问题；综合形态、孢粉、细胞与分子资料，阐明叉蕨属的概念和属下分类。项目的开展，将解决叉蕨属概念争议，奠定叉蕨属和叉蕨科的系统学基础；揭示叉蕨属的杂交现象和杂交对于该属系统演化的贡献；促进《中国植物志》的修订，利于中国热带蕨类植物多样性认识和保护。

叉蕨属是一个热带分布的蕨类大属，属的分类学范畴一直争论不断。我国虽然不是叉蕨属的主要分布区，但是，中国叉蕨属缺乏现代分类学研究，不少种的名实混乱、相近种难以区分。针对这些问题，我们开展了详细的宏观形态学性状研究、孢子形态和染色体资料调查、以及基于叶绿体基因序列的分子系统学研究。研究结果表明，广义叉蕨属是一个单系类群，此前分类地位有争议的Ctenitopsis, Hemigramma, Quercifilix和Stenosemia, 以及广为接受的Heterogonium, Psomiocarpa和Tectaridium等7个属均应归入叉蕨属；单系的叉蕨属被解析为4个演化支，其中有1支发生在新大陆（美洲），另外3支发生在旧大陆；宏观形态上，叶脉式样、叶的分裂、叶片顶部形态和孢子囊群的排列是叉蕨属最有用的几个分类性状，这4个性状也有一定的系统学意义，但它们都不是一次起源的；叉蕨属的孢子都是单裂缝的椭圆球形，大小介于24--38 × 21--32 μm之间，表面有丰富纹饰，孢子周壁纹饰分化为两大基本式样，即脊状孢子和翅状孢子，孢子周壁纹饰也具有一定的分类和系统学价值；细胞学上，中国叉蕨属约70%的种类是二倍体，2n = 80，目前发现有2个种（凌乐叉蕨和香港叉蕨）为三倍体, 3个种（下延叉蕨、疣状叉蕨、多形叉蕨）兼具二倍体和四倍体，1个种（芽胞叉蕨）兼具二、三、四倍体；分类修订澄清了许多种的名实混乱，确认中国有39种叉蕨属植物，其中包含3个新种和2个中国新分布种。我们在世界范围内首次构建了叉蕨属的系统发育，提出广义叉蕨属才是单系类群的概念，阐明了各形态性状的变异式样和分类学意义，澄清了中国叉蕨属的分类和大多数种的细胞倍性，这些工作对于深入认识叉蕨属的物种多样性和系统发育具有重要的科学意义。