Trapelioid fungi constitute a widespread group of mostly crust-forming lichen mycobionts that are key to understanding the early evolutionary splits in the Ostropomycetidae, the second-most species-rich subclass of lichenized Ascomycota. The uncertain phylogenetic resolution of the approximately 170 species referred to this group contributes to a poorly resolved backbone for the entire subclass. Based on a data set including 657 newly generated sequences from four ribosomal and four protein-coding gene loci, we tested a series of a priori and new evolutionary hypotheses regarding the relationships of trapelioid clades within Ostropomycetidae. We found strong support for a monophyletic group of nine core trapelioid genera but no statistical support to reject the long-standing hypothesis that trapelioid genera are sister to Baeomycetaceae or Hymeneliaceae. However, we can reject a sister group relationship to Ostropales with high confidence. Our data also shed light on several long-standing questions, recovering Anamylopsoraceae nested within Baeomycetaceae, elucidating two major monophyletic groups within trapelioids (recognized here as Trapeliaceae and Xylographaceae), and rejecting the monophyly of the genus Rimularia. We transfer eleven species of the latter genus to Lambiella and describe the genus Parainoa to accommodate a previously misunderstood species of Trapeliopsis. Past phylogenetic studies in Ostropomycetidae have invoked “divergence order” for drawing taxonomic conclusions on higher level taxa. Our data show that if backbone support is lacking, contrasting solutions may be recovered with different or added data. We accordingly urge caution in concluding evolutionary relationships from unresolved phylogenies.

中文翻译：

---

诊断有问题的骨干：在骨菌科（Lecanoromycetes）的大规模系统发育中测试梯形地衣真菌的拓扑假设。


梯形真菌构成了一个广泛分布的类群，主要是形成地壳的地衣真菌生物体，它们对于理解骨真菌科（地衣子囊菌门第二个物种最丰富的亚类）的早期进化分裂至关重要。该类群中约 170 个物种的系统发育分辨率不确定，导致整个亚纲的主干结构解析不佳。基于包含来自四个核糖体和四个蛋白质编码基因位点的 657 个新生成序列的数据集，我们测试了一系列关于骨霉菌科内梯形分支关系的先验和新的进化假设。我们发现了对由九个核心梯形属组成的单系群的有力支持，但没有统计支持来拒绝长期以来的假设，即梯形属是 Baeomycetaceae 或 Hymeneliaceae 的姐妹。然而，我们可以高度自信地拒绝与奥斯特罗帕莱斯的姐妹群体关系。我们的数据还揭示了几个长期存在的问题，恢复了嵌套在Baeomycetaceae中的Anamylopsoraceae，阐明了斜方科中两个主要的单系类群（这里被识别为Trapeliaceae和Xylographaceae），并拒绝了Rimularia属的单系。我们将后一个属的 11 个物种转移到Lambiella中，并描述了Parainoa属以适应以前被误解的Trapeliopsis物种。过去对骨霉菌科的系统发育研究引用了“分歧顺序”来得出更高级别分类群的分类学结论。我们的数据表明，如果缺乏主干支持，可以使用不同或添加的数据来恢复对比解决方案。因此，我们敦促在从未解决的系统发育中得出进化关系时要谨慎。