地钱纲分类系统和中国地钱纲植物的修订

Marchantiopsida, i.e. complex thalloid liverworts, is a unique group with air pores and air chambers of the gametophytes in bryophytes. Most species in the group have a very short life cycle for an adaptation in a quick changing environment. At present Marchantiopsida contains about 364 species in 36 genera of 20 families，it has the richest endemic taxa and endangered taxa of bryophytes. It is the taxonomically most difficult group in unpublished Bryoflora of China, and it has also been still poorly known in most areas in the world. China is one of its diversity distribution centers with 83 species in 22 genera of 14 families, but about 1/4 species locally endemic. Owing to the difficult taxonomy, elusive growing seasons and the lack of special investigation, the exact number of species of this group seems to be inestimable. By the combined methods of morphological taxonomy, molecular systematics and biogeography we will carry out an intensive revision of Chinese Marchantiopsida, establish a more natural classification system, revise the taxonomic circumscriptions, reveal the exact species number of China and endangered status, and explore distribution patterns and their origins by intensive field collections, sequences of nucleus and chloroplast genes, and ancestral state reconstructions and character analyses. The project will provide the scientific evidence for the conservation and uses of bryophyte diversity.

地钱纲（Marchantiopsida）是苔藓植物中唯一一类配子体具有气孔和气室分化的类群，也称“复杂叶状体苔类”，多数种类以短命的生活史适应快速变化的环境。地钱纲目前约有20科、36属、364种，是苔藓植物中特有种和濒危种最丰富的类群，也是中国苔藓志遗留的最困难类群，在世界绝大多数地区也仍然缺乏对其物种多样性的确切了解。我国是地钱纲植物的分布中心之一，目前记载的有14科22属83种，但有近1/4的种为我国特有。但由于分类的困难、难以琢磨的生长季节以及缺乏专门的调查，我国拥有的确切物种数量难以估计。本项目拟以经典分类、分子系统学和生物地理相结合的研究方法，通过广泛而深入的野外调查、对核和叶绿体相关基因的测序以及祖先性状重建和形态特征分析，完善世界地钱纲植物的分类系统，揭示我国地钱纲植物确切的物种数量和濒危状况，探讨分布格局和成因，为苔藓植物多样性的保护和利用提供新的科学依据。

地钱纲(复杂叶状体苔类)是苔藓植物中唯一一类配子体具有气孔和气室分化的类群，是了解早期陆地植物进化的关键类群，然而它也是我国苔藓志遗留的最困难类群。建立完善和可靠的分类系统和揭示我国的物种多样性和分布是地钱纲研究一项最基础和迫切的任务。本项目通过对我国广泛深入的采样以及国外关键材料的获得，对87种197份材料作了6个叶绿体基因片段(atpB, psbA, rbcL,rpoC1,rps4和trnL-F)以及两个核基因片段(nr26S和nrITS)的测序，并对代表地钱纲所有目和几乎所有科和属的70份标本作了叶绿体基因组测序，基于光学和扫描电镜的观察结果，运用分类学、分子系统发育和系统发育基因组学的整合分析，(1)澄清了地钱纲各科属的系统位置关系，建立了更可靠和完善的世界地钱纲分类系统，(2)揭示了光苔科的分布式样，(3)发现了2个新属（拟花萼苔属、类石地钱属）和14个新种（四姑娘山囊果苔、拟长毛钱苔等），(4)首次归并了1个目(半月苔目)、1个科（假钱苔科）和3个种，(5)增加了1个新记录目（囊果苔目）和11个新记录种，(6)证实我国有地钱纲植物14科25属103种。本项目基本摸清了我国地钱纲植物物种多样性的家底，研究结果丰富了我国苔藓植物的物种多样性，为苔藓植物的物种多样性保护提供了重要的科学依据。