中国新记录——毛齿藓短蒴变种(新拟)

Trichodon cylindricus var.oblongus(Lindb.)Podp.(Ditrichaceae,Musci)Reported New to China

该研究首次报道了毛齿藓短蒴变种(新拟)在中国的分布和毛齿藓属在新疆的分布。研究表明:(1)毛齿藓短蒴变种的主要识别特征为:叶基部鞘状,突然狭窄成线状披针形,背仰,叶缘平展,中肋充满叶上部,背面粗糙,远轴面有厚壁细胞束分化,叶细胞长方形至短长方形;有假根生芽胞;孢蒴椭球形,稍弓形弯曲,蒴齿线状披针形,二裂至近基部。(2)毛齿藓属的3个分类单位在中国均有分布,毛齿藓短蒴变种以较短的孢蒴和蒴柄区别于原变种,以有根生芽胞、叶基部呈明显鞘状、叶缘平展区别于云南毛齿藓的无假根生芽胞、叶基部略呈鞘状、叶缘背卷。(3)在牛毛藓科中有许多类群与毛齿藓短蒴变种形态相似,但仅有毛齿藓属的叶在横切面上主细胞的远轴面有厚壁细胞束,而其他类群的叶在横切上主细胞的近轴面和远轴面均有厚壁细胞束。该变种的叶背仰不同于牛毛藓科其他属的叶直立;以具鞘部的叶、表面光滑的孢蒴、内弯的蒴齿区别于无鞘部的叶、表面有纵沟槽的孢蒴、直立的蒴齿的牛毛藓属。(4)该变种属北极-高山分布类型,表现出了明显的欧洲-亚洲-北美洲间断分布模式,可作为研究气候变化、海陆变迁的重要材料。

This is the first report to Trichodon cylindricus var.oblongus in China,and the genus Trichodon to the Xinjiang Uygur Autonomous Region.The study showed that:(1)the variety is characterized by the leaves wide-spreading when moist,with a broad and sheathing base,rather abruptly narrowed to a long,linear subula,plane margins,costa filling most of the subula,rough at back,a stereid band on abaxial of guide cells,leaf cells rectangular to short-rectangular;tubers on rhizoids;ellipsoidal capsule slightly curved,with linear-lanceolate segments divided into two nearly to base.(2)There are three taxa of Trichodon in China up to now.T.cylindricus var.oblongus can be easily separated to var.cylindricus by shorter seta and capsule.T.cylindricus var.oblongus is characterized by the tuber present,leaf with sheathing base,plane margins,while T.muricatus Herzog is characterized by tuber absent,leaf with slightly sheathing base,recurved margins.(3)In Ditrichaceae,many genera have stereid band on both adaxial and abaxial sides of guide cells.Just genus Trichodon has stereid band differentiate only on abaxial side.T.cylindricus var.oblongus has squarrose leaves versus other genera of Ditrichaceae have erect leaves or nearly so.It has leaf with sheathing base,smooth capsule when dry,and incurved segments of peristome versus the genus Ditrichum has leaf without sheathing base,strongly furrowed capsule when dry,and straight segments of peristome.(4)Trichodon cylindricus var.oblongus is a dispersed type to arctic-alpine.It is a disjunctly distributed species on Europe-Asia-North America continent.The taxon may be viewed as an indicator in research for climate change and the transformation between sea and continent.