为探讨缺齿藓类与真藓科、提灯藓科的系统关系，理清缺齿藓科的系统位置和中国缺齿藓科分类问题，该研究以中国分布的缺齿藓科植物和相关类群4000余份标本为材料，进行详细的形态学研究，并选用其中35种、40份样品的4个DNA片段（rps4、trnG、trnL-trnF 、atpB-rbcL）联合数据用于分子系统分析，采用邻接法（NJ）和最大似然法（ML）构建分子树。结果表明：（1）在分子树中，缺齿藓类与真藓科植物分别聚在具有高支持率的不同分支上，叶形、叶细胞等形态学特征也有较大差异，缺齿藓类应从广义的真藓科分出。（2）在分子树中，虽然缺齿藓类与提灯藓科植物聚在同一分支中，但无形态学的共源性状，二者不应视为一个单系类群。（3）缺齿藓科是一个自然类群，缺齿藓科内属间存在着密切的系统关系，缺齿藓科的主要识别特征为：植物体小型，茎常分枝；叶形和叶细胞为丝瓜藓型（Pohlia-like），披针形至长椭圆形，中上部细胞狭长，线状菱形或蠕虫形；生殖苞多生于新生枝顶；蒴齿为互生双齿层，常有不同程度的退化或一层蒴齿缺失，稀双层蒴齿缺失。（4）中国缺齿藓科包含有5属，即缺齿藓属（Mielichhoferia）、丝瓜藓属（Pohlia）、拟丝瓜藓属（Pseudopohlia）、合齿藓属（Synthetodontium）和小叶藓属（Epipterygium），目前为止共计34种（含种下分类单位）。%The paper aims to discuss the relationship between Mielichhoferiagroup and Bryaceae ,to identi-fy morphological synapomorphy between Mielichhoferiagroup and Mniaceae ,to solve the problem of sys-tematic position of Mielichhoferia group ,to figure out the classification of Mielichhoferiaceae in China . Morphological characters of more than 4 000 specimens of Mielichhoferiaceae and its related groups in Chi-na were analyzed .And then ,neighbor joining (NJ) and maximum likelihood (ML) tree were built based on combined trnG , rps4 , trnL-trnF ,and atpB-rbcL cpDNA sequences of 40 specimens for 35 species . Combining morphological and molecular data in the analyses showed that :(1) not only were Mielichho f e-ria group and Bryaceae family in the different clades in the molecular tree ,but also morphological features , such as the leaf shape ,the leaf cells of the two groups were different .Mielichho f eria group should be sep-arated from Bryaceae .(2) No morphological synapomorphy can be detected for Mielichho f eria group and Mniaceae family ,although they were in the same clade in the molecular tree .The two groups were not monophyletic .(3) Mielichhoferiaceae is a natural monophyletic group .In Mielichhoferiaceae ,the plants are small ,stems tend to be much branched than in Bryaceae ;leaves are Pohlia-like in shape and areola-tion;gametangia are often produced on lateral branches or the base of stems ;peristome is diplolepideous-alternate ,often reduced to one layer or rarely absent .(4) There are five genera ,Mielichhoferia ,Pohlia , Pseudopohlia ,Synthetodontium and Epipterygium ,in Mielichhoferiaceae in China ,total 32 species and 2 variaties .
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