Anaspidacea is probably the most enigmatic higher taxon within the Malacostraca. Representatives of the genus Anaspides are often considered "living fossils" due to their strong resemblance to their Triassic relatives. In comparison to other extant Malacostraca, they possess a high number of plesiomorphic characters. Anaspidacea are often combined with another freshwater taxon, Bathynellacea, into the Syncarida, but actual evidence for monophyletic Syncarida is weak. Other potential sister groups are Eucarida, Euphausiacea, or Euphausiacea + Peracarida. Like Euphausiacea, Mysidacea and "natant" decapods, Anaspidacea show what has been called a "caridoid facies". In malacostracan crustaceans, a prominent mode of locomotion is swimming, as it almost certainly was for the malacostracans' common ancestor. However, when considered in detail, swimming is found to take quite different forms in the various taxa. To obtain a better understanding of the evolution of swimming, we analyzed locomotion in several species of Anaspides endemic to Tasmania. The morphology of the protopodal and exopodal musculature as well as the exo- and endoskeletal structures of the thoracopods were examined using 3D reconstruction of CLSM- and μCT data. Various aspects of locomotion were documented and described using recording techniques including in-habitat underwater filming and macro high-speed recording. Our analysis shows the high level of complexity of the muscular arrangement and skeletal construction in the thoracopods of these - in many regards plesiomorphic - malacostracans, and demonstrates the presence of epipodal musculature. Our recordings provide insight into various aspects of locomotion of Anaspides, including the congruence of locomotive kinematics in swimming and walking. Our morphological findings and observations on locomotion in Anaspides are compared to findings in other malacostracan shrimps and discussed in a phylogenetic context, with our analysis providing further support for Xenommacarida (sensuRichter, 1999: Anaspidacea + Euphausiacea + Peracarida). Further, a new hypothesis for the origin of the ventral brood pouch, the marsupium, of Peracarida is discussed. On the basis of a comparison of their morphology and biology, the oostegites which form the marsupium are suggested to be derived thoracopodal endites as present in female Anaspides. Finally, an evolutionary scenario is presented and mapped on a cladogram in which the evolution of malacostracan swimming from a common caridoid ancestor up to the different taxa present today is discussed.

中文翻译：

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Anaspides (Anaspidacea, Malacostraca) 的运动——来自胸足类的形态功能 st 的见解以及对游泳和步行的一些观察

Anaspidacea 可能是 Malacostraca 中最神秘的高等分类群。Anaspides 属的代表通常被认为是“活化石”，因为它们与三叠纪的亲戚非常相似。与其他现存的 Malacostraca 相比，它们拥有大量的拟形特征。Anaspidacea 经常与另一种淡水分类群 Bathynellacea 结合到 Syncarida 中，但单系 Syncarida 的实际证据很弱。其他潜在的姊妹类群有 Eucarida、Euphausiacea 或 Euphausiacea + Peracarida。像 Euphausiacea、Mysidacea 和“natant”十足目动物一样，Anaspidacea 显示出所谓的“caridoid facies”。在马拉科斯特拉科甲壳类动物中，一种突出的运动方式是游泳，这几乎可以肯定是马拉科斯特拉科动物的共同祖先。然而，如果仔细考虑，会发现游泳在不同的分类群中呈现出截然不同的形式。为了更好地了解游泳的进化，我们分析了塔斯马尼亚特有的几种 Anaspides 的运动。使用 CLSM 和 μCT 数据的 3D 重建检查原足和外足肌肉组织的形态以及胸足类的外骨骼和内骨骼结构。使用记录技术记录和描述了运动的各个方面，包括栖息地水下拍摄和宏观高速记录。我们的分析显示了这些胸足类（在许多方面都是拟形的）的肌肉排列和骨骼构造的高度复杂性，并证明了足底肌肉组织的存在。我们的录音提供了对 Anaspides 运动的各个方面的洞察，包括游泳和步行中运动学的一致性。我们的形态学发现和对 Anaspides 运动的观察与其他马拉科斯特拉康虾的发现进行了比较，并在系统发育背景下进行了讨论，我们的分析为 Xenomacarida 提供了进一步的支持 (sensuRichter, 1999: Anaspidacea + Euphausiacea + Peracarida)。此外，还讨论了关于 Peracarida 腹侧育雏袋有袋动物起源的新假设。根据对它们的形态和生物学的比较，建议形成有袋类动物的 oostegites 是源自雌性 Anaspides 中的胸足类动物。最后，