Only a few studies have examined the visual systems of Amblypygi (whip spiders) until now. To get new insights suitable for phylogenetic analysis we studied the axonal trajectories and neuropil architecture of the visual systems of several whip spider species (Heterophrynus elaphus, Damon medius, Phrynus pseudoparvulus, and P. marginemaculatus) with different neuroanatomical techniques. The R-cell axon terminals were identified with Cobalt fills. To describe the morphology of the visual neuropils and of the protocerebrum generally we used Wigglesworth stains and μCT. The visual system of whip spiders comprises one pair of median and three pairs of lateral eyes. The R-cells of both eye types terminate each in a first and a second visual neuropil. Furthermore, a few R-cell fibres from the median eyes leave the second median eye visual neuropil and terminate in the second lateral eye neuropil. This means R-cell terminals from the lateral eyes and the median eyes overlap. Additionally, the arcuate body and the mushroom bodies are described. A detailed comparison of our findings with previously studied chelicerate visual systems (i.e., Xiphosura, Scorpiones, Pseudoscorpiones, Opiliones, and Araneae) seem to support the idea of close evolutionary relationships between Xiphosura, Scorpiones, and Amblypygi.

中文翻译：

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也像鲎？– Amblypygi（鞭蜘蛛）的视网膜轴突和视觉神经纤维

到目前为止，只有少数研究检查了 Amblypygi（鞭蜘蛛）的视觉系统。为了获得适合系统发育分析的新见解，我们使用不同的神经解剖技术研究了几种鞭蜘蛛（Heterophrynus elaphus、Damon medius、Phrynus fakeparvulus 和 P. marginemaculatus）视觉系统的轴突轨迹和神经纤维结构。R 细胞轴突末端用钴填充物进行识别。为了描述视觉神经纤维和原大脑的形态，我们通常使用 Wigglesworth 染色和 μCT。鞭蜘蛛的视觉系统包括一对中眼和三对侧眼。两种眼睛类型的 R 细胞均终止于第一和第二视觉神经元。此外，来自正中眼的一些 R 细胞纤维离开第二正中眼视觉神经纤维并终止于第二侧眼神经纤维。这意味着侧眼和正中眼的 R 细胞末端重叠。另外，还描述了弓形体和蘑菇体。我们的研究结果与之前研究的螯肢动物视觉系统（即剑尾目、蝎目、拟蝎目、Opiliones 和蜘蛛目）的详细比较似乎支持剑尾目、蝎目和钝尾目之间密切进化关系的观点。