Subaerial green microalgae represent a polyphyletic complex of organisms, whose genetic diversity is much higher than their simple morphologies suggest. The order Trentepohliales is the only species-rich group of subaerial algae belonging to the class Ulvophyceae and represents an ideal model taxon to investigate evolutionary patterns of these organisms. We studied phylogenetic relationships in two common genera of Trentepohliales (Trentepohlia and Printzina) by separate and combined analyses of the rbcL and 18S rRNA genes. Trentepohlia and Printzina were not resolved as monophyletic groups. Three main clades were recovered in all analyses, but none corresponded to any trentepohlialean genus as defined based on morphological grounds. The rbcL and 18S rRNA datasets provided congruent phylogenetic signals and similar topologies were recovered in single-gene analyses. Analyses performed on the combined 2-gene dataset inferred generally higher nodal support. The results clarified several taxonomic problems and showed that the evolution of these algae has been characterized by considerable morphological convergence. Trentepohlia abietina and T. flava were shown to be separate species from T. aurea; Printzina lagenifera, T. arborum and T. umbrina were resolved as polyphyletic taxa, whose vegetative morphology appears to have evolved independently in separate lineages. Incongruence between phylogenetic relationships and traditional morphological classification was demonstrated, showing that the morphological characters commonly used in the taxonomy of the Trentepohliales are phylogenetically irrelevant.

中文翻译：

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系统发育关系和物种限定在Trentepohlia和Printzina（Trentepohliales，绿藻）。

空中绿色藻类代表生物的多系复合体，其遗传多样性远高于其简单形态所暗示的。Trentepohliales阶是唯一属于藻类科的海藻藻类，是唯一一个物种丰富的群体，它是研究这些生物进化模式的理想模型分类群。我们通过对rbcL和18S rRNA基因进行单独和组合分析，研究了特兰氏菌属（Trentepohliales和Printzina）的两个常见属的系统发生关系。Trentepohlia和Printzina没有被确定为单系统群体。在所有分析中均回收了三个主要进化枝，但没有一个对应于形态学依据定义的任何锯齿形纲属。rbcL和18S rRNA数据集提供了一致的系统发育信号，并且在单基因分析中回收了相似的拓扑。对组合的2基因数据集进行的分析推断通常更高的节点支持度。结果澄清了几个分类学问题，并表明这些藻类的进化已具有相当的形态学收敛特征。Trentepohlia abietina和T. flava被证明是与T. aurea分离的物种。紫花苜蓿，紫杉和伞形藻被解析为多系类群，其营养形态似乎在不同的谱系中独立发展。系统发育关系和传统形态学分类之间的不一致，