Divakar Pradeep K, Crespo Ana, Blanco Oscar, Lumbsch H Thorsten
Departamento de Biologia Vegetal II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid 28040, Spain.
Mol Phylogenet Evol. 2006 Aug;40(2):448-58. doi: 10.1016/j.ympev.2006.03.024. Epub 2006 May 2.
Lichen-forming ascomycetes exhibit often complex morphologies of the vegetative thallus that are usually not found in non-lichenized fungi. This includes the thallus organization and appendical structures associated with the main thallus, such as cilia and rhizines. Such morphological characters are widely employed in the taxonomy of parmelioid lichens, especially at generic level. Within parmelioid lichens, several monophyletic groups can be distinguished, the Hypotrachyna clade being one of them, which includes mostly tropical taxa. In this first molecular study focused specifically on the Hypotrachyna clade, we used maximum parsimony and Bayesian analyses of a combined data set of nuclear ITS and mitochondrial SSU rDNA sequences to (1) test the monophyly of genera presently accepted within the clade and (2) evaluate the phylogenetic value of the morphological characters used to circumscribe genera in parmelioid lichens. Out of the 89 mtSSU and 88 nuITS sequences included in the present study, 121 sequences were newly obtained. Our results show that the taxa within the clade fall into two major groups and that the genus Hypotrachyna is polyphyletic. Everniastrum and Parmelinopsis are nested within Hypotrachyna sensu stricto, the latter being also polyphyletic. Bulbothrix is paraphyletic with Parmelinella nested within and is basal to the second major Hypotrachyna clade. Monophylies of Bulbothrix and Hypotrachyna are significantly rejected. The phylogenetic analysis demonstrates that morphological characters currently used to circumscribe genera in parmelioid lichens, such as cortical anatomy, lobe configuration, cilia, and rhizines have been overestimated and have only minor value in identifying monophyletic groups.
形成地衣的子囊菌通常具有复杂的营养体地衣体形态，这在非地衣化真菌中通常是找不到的。这包括地衣体结构以及与主要地衣体相关的附属结构，如纤毛和假根。这些形态特征在拟盘叶衣属地衣的分类中被广泛应用，尤其是在属级水平上。在拟盘叶衣属地衣中，可以区分出几个单系类群，其中Hypotrachyna分支就是其中之一，它主要包括热带类群。在这项首次专门针对Hypotrachyna分支的分子研究中，我们使用最大简约法和贝叶斯分析法对核ITS和线粒体SSU rDNA序列的组合数据集进行分析，以（1）检验该分支内目前公认的属的单系性，以及（2）评估用于界定拟盘叶衣属地衣属的形态特征的系统发育价值。在本研究纳入的89个mtSSU和88个nuITS序列中，有121个序列是新获得的。我们的结果表明，该分支内的类群分为两个主要类群，并且Hypotrachyna属是多系的。扁枝衣属和拟盘叶衣属嵌套在狭义的Hypotrachyna属内，后者也是多系的。小孢发属是并系的，其中巢状包含了小孢盘叶衣属，并且位于第二个主要的Hypotrachyna分支的基部。小孢发属和Hypotrachyna属的单系性被显著否定。系统发育分析表明，目前用于界定拟盘叶衣属地衣属的形态特征，如皮层解剖结构、裂片形态、纤毛和假根，被高估了，在识别单系类群方面只有很小的价值。
