Strauß Johannes
AG Integrative Sensory Physiology, Institute for Animal Physiology, Justus Liebig University Gießen, Gießen, Germany.
Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Gießen, Gießen, Germany.
Brain Behav Evol. 2023;98(1):22-31. doi: 10.1159/000525323. Epub 2022 Jun 2.
The subgenual organ complex in the leg of Polyneoptera (Insecta) consists of several chordotonal organs specialized to detect mechanical stimuli from substrate vibrations and airborne sound. In stick insects (Phasmatodea), the subgenual organ complex contains the subgenual organ and the distal organ located distally to the subgenual organ. The subgenual organ is a highly sensitive detector for substrate vibrations. The distal organ has a characteristic linear organization of sensilla and likely also responds to substrate vibrations. Despite its unique combination of sensory organs, the neuroanatomy of the subgenual organ complex of stick insects has been investigated for only very few species so far. Phylogenomic analysis has established for Phasmatodea the early branching of the sister groups Oriophasmata, the Old World phasmids, and Occidophasmata, the New World phasmids. The species studied for the sensory neuroanatomy, including the Indian stick insect Carausius morosus, belong to the Old World stick insects. Here, the neuroanatomy of the subgenual organ complex is presented for a first species of the New World stick insects, the Peruvian stick insect Oreophoetes peruana. To document the sensory organs in the subgenual organ complex and their innervation pattern, and to compare these between females and males of this species and also to the Old World stick insects, axonal tracing is used. This study documents the same sensory organs for O. peruana, subgenual organ and distal organ, as in other stick insects. Between the sexes of this species, there are no notable differences in the neuroanatomy of their sensory organs. The innervation pattern of tibial nerve branches in O. peruana is identical to other stick insect species, although the innervation pattern of the subgenual organ by a single tibial nerve branch is simpler. The shared organization of the organs in the subgenual organ complex in both groups of Neophasmatodea (Old World and New World stick insects) indicates the sensory importance of the subgenual organ but also of the distal organ. Some variation exists in the innervation of the chordotonal organs in O. peruana though a common innervation pattern can be identified. The findings raise the question for the ancestral neuroanatomical organization and innervation in stick insects.
多食亚目（昆虫纲）腿部的膝下器复合体由几个弦音器组成，这些弦音器专门用于检测来自基质振动和空气传播声音的机械刺激。在竹节虫（竹节虫目）中，膝下器复合体包含膝下器和位于膝下器远端的远端器。膝下器是基质振动的高灵敏度探测器。远端器具有独特的感觉器线性排列，可能也对基质振动有反应。尽管其感觉器官组合独特，但到目前为止，仅对极少数竹节虫物种的膝下器复合体神经解剖学进行了研究。系统基因组分析已确定，在竹节虫目中，姐妹类群东方竹节虫（旧世界竹节虫）和西方竹节虫（新世界竹节虫）是早期分支。用于感觉神经解剖学研究的物种，包括印度竹节虫印度绿竹节虫，都属于旧世界竹节虫。在此，首次呈现了新世界竹节虫秘鲁竹节虫膝下器复合体的神经解剖学。为了记录膝下器复合体中的感觉器官及其神经支配模式，并比较该物种雌雄个体之间以及与旧世界竹节虫的差异，采用了轴突追踪法。这项研究记录了秘鲁竹节虫与其他竹节虫相同的感觉器官，即膝下器和远端器。在该物种的雌雄个体之间，其感觉器官的神经解剖学没有显著差异。秘鲁竹节虫胫神经分支的神经支配模式与其他竹节虫物种相同，尽管单个胫神经分支对膝下器的神经支配模式更简单。新竹节虫类群（旧世界和新世界竹节虫）膝下器复合体中器官的共同组织表明了膝下器以及远端器在感觉方面的重要性。虽然可以识别出一种常见的神经支配模式，但秘鲁竹节虫的弦音器神经支配存在一些变异。这些发现引发了关于竹节虫祖先神经解剖组织和神经支配的问题。
