To better understand insect evolution, fossils – mainly known by their wings – must be used as terminals in phylogenetic analyses. Such analyses are, however, rarely performed because of a lack of consensus on the homology of venation in insects. Researchers do not agree with the current concept on the exact number and identity of the main veins. Here, we confirm the presence, which has been in question since the early 20th century, of an independent main postcubital vein (PCu vein) between the cubital and anal veins (29 fossil and extant examined orders; > 85% of observed insects). The PCu vein corresponds to the so‐called vein 1A or first anal vein. It is easily identified by the unique shape of its bulla. It may have several branches and be partially fused with the cubital and anal veins. Once the PCu vein was identified, we reconsidered as an example the particular case of the Phasmatodea, showing that extant stick insects have a unique venation among insects, with a reduced median vein and a simple cubital vein adjacent or fused to the PCu vein. This study is a new approach towards resolving wing vein homology issues, crucial for future large‐scale phylogenetic analyses in insects combining extant and extinct taxa.

中文翻译：

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存在与否：显微断层扫描显示昆虫的肘后静脉

为了更好地了解昆虫进化，化石——主要是它们的翅膀——必须用作系统发育分析的终端。然而，由于对昆虫脉络的同源性缺乏共识，这种分析很少进行。研究人员不同意目前关于主要静脉的确切数量和身份的概念。在这里，我们确认了自 20 世纪初以来一直存在问题的存在，在肘静脉和肛门静脉之间存在独立的主肘后静脉（PCu 静脉）（29 个化石和现存的检查目；> 85% 的观察到的昆虫）。PCu 静脉对应于所谓的静脉 1A 或第一肛门静脉。它的大泡的独特形状很容易识别。它可能有几个分支，并与肘静脉和肛静脉部分融合。一旦确定了 PCu 静脉，作为一个例子，我们重新考虑了 Phasmatodea 的特殊情况，表明现存的竹节虫在昆虫中具有独特的脉络，具有减少的正中静脉和与 PCu 静脉相邻或融合的简单肘静脉。这项研究是解决翼脉同源性问题的新方法，对于结合现存和灭绝分类群的昆虫的未来大规模系统发育分析至关重要。