Elucidating the phylogeny of the Diplopoda: microCT-scans, morphology and morphometrics of all millipede orders

千足虫（倍足纲）是最古老的陆地多细胞生物之一，已描述的物种有12.000种，是陆地第三大类节肢动物。作为食草动物，它们在分解和土壤形成方面发挥着重要作用。尽管他们的系统发育年龄和他们的明显价值，以了解早期殖民的土地，diplopodan形态是严重不足的研究。这对于16个千足虫目中的稀有代表尤其如此，例如Siphoniulida，Glomeridesmida或Siphonocryptida。事实上，许多作者抱怨说，我们对倍足动物的形态学知识已经达到了100年前对六足动物，甲壳动物和蛛形纲动物的相同水平。通过这个项目，我们将部分克服形态学知识的不足。使用同步加速器显微计算机断层扫描和组织学的结合，我们手头的工具，把我们的千足虫形态的知识到一个新的水平。我们的目标是首先提供一个数字化的，开源的注释库的同步micro-CT扫描和3D模型，超过48个代表的所有主要群体内倍足类，这将涵盖大部分的形态和系统发育的多样性。其次，我们将使用这种比较形态学信息，以促进一个有充分根据的系统发育。在这个框架内，我们将特别关注形态特征系统，如口器，内骨骼，生殖器结构和气管袋配置。在第三步中，我们将使用几何形态测量方法来定量研究所选字符系统内的进化形状变化，（a）系统发育信号，（B）进化异速生长和（c）形状变化与各种生态因子的潜在相关性。这将增加我们对形态变化的理解，以应对与千足虫相关的特定环境，这将使我们能够重建倍足类祖先首次殖民土地的祖先条件。我们的贡献将提供有关一个物种丰富的节肢动物组的关键形态适应信息。

Millipedes (Diplopoda) are among the oldest terrestrial multicellular organisms, and with 12.000 described species the third largest class of land arthropods. As detritivores they play an important role for decomposition and soil formation. Despite their phylogenetic age and their obvious value to understand the early colonization of the land, the diplopodan morphology is severely understudied. This is especially true for the rare representatives among the 16 millipede orders, such as Siphoniulida, Glomeridesmida, or Siphonocryptida. In fact, numerous authors complained that our morphological knowledge of the Diplopoda is at the same level reached for Hexapoda, Crustacea, and Arachnida already 100 years ago. With this project, we will partly overcome this deficit in morphological knowledge. Using a combination of synchrotron micro-computed tomography and histology, we have the tools at hand to take our knowledge of the morphology of millipedes to the next level. Our aim is to first provide a digital, open-source annotated library of synchroton micro-CT scans and 3D-models for more than 48 representatives of all main groups within Diplopoda, which will cover large parts of their morphological and phylogenetic diversity. Secondly, we will use this comparative morphological information to contribute to a well-founded phylogeny. Within this framework, we will especially focus on morphological character systems, such as mouthparts, endoskeleton, genital structures, and tracheal pouch configuration. In a third step, we will use a geometric morphometric approach to quantitatively investigate evolutionary shape variations within the chosen character systems with regards to (a) phylogenetic signal, (b) evolutionary allometry and (c) potential correlation of shape variation with various ecological factors. This will increase our understanding of morphological changes in response to the particular environment relevant for millipedes, which will enable us to reconstruct the ancestral conditions under which ancestors of the Diplopoda first colonized land. Our contribution will provide information about key morphological adaptations for a species-rich group of arthropods.