Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan.
Graduate School of Science and Technology, and Department of Mathematical and Systems Engineering, Shizuoka University, Hamamatsu, 432-8561, Japan.
Sci Rep. 2019 Apr 30;9(1):6722. doi: 10.1038/s41598-019-43175-w.
The tentorium is the internal skeleton of the head capsule of insects. Several studies have shown that the structure of the tentorium is an important factor not only for the morphology and systematics but also for the phylogeny and evolution. In ants, however, only three studies have reported tentorial morphology so far. We reveal the fundamental structure of the tentorium of the genus Lasius (Hymenoptera, Formicidae) and its minor variation among six species of the genus. Based on the results, we give new terminologies of the organ, presenting a schematic diagram of the tentorium. We clarify muscle attachment to the tentorium by constructing a three-dimension image of the tentorium and muscles. We then verify the attachment areas of the antennal muscles and maxillary adductor muscles on the tentorium. The results show that the muscular attachment areas are broader than previously thought. Our study indicates that the key to understanding the evolution of the tentorium is its functional morphology, in relation to the attachments of the muscles originating from the tentorium within the head capsule. This is the first report of the three-dimensional images of the ant tentorium and its attached muscles. The intra- and inter-specific variations of the tentorium is also reported for the first time.
天幕是昆虫头壳的内骨骼。有几项研究表明，天幕的结构不仅对形态学和系统学很重要，而且对系统发育和进化也很重要。然而，到目前为止，在蚂蚁中，只有三项研究报告了天幕的形态。我们揭示了 Lasius 属（膜翅目，蚁科）天幕的基本结构及其六个种之间的微小变化。基于这些结果，我们给出了该器官的新术语，并展示了天幕的示意图。我们通过构建天幕和肌肉的三维图像来阐明天幕上肌肉的附着点。然后，我们验证了触角肌和上颚肌在天幕上的附着区域。结果表明，肌肉附着区域比之前认为的要宽。我们的研究表明，理解天幕进化的关键是它的功能形态，这与起源于头壳内天幕的肌肉的附着有关。这是首次报告蚂蚁天幕及其附着肌肉的三维图像。同时，也首次报告了天幕的种内和种间变异。
