Cheng Zixin, Yoshizawa Kazunori
Systematic Entomology, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
J Morphol. 2019 Apr;280(4):555-567. doi: 10.1002/jmor.20965. Epub 2019 Feb 18.
Although the great genital diversity of the barklouse genus Trichadenotecnum has been described in previous studies, the specific function of the genital structures during the copulation process has received less investigative attention. We reconstructed 3D-models of each structure of the male and female genitalia of Trichadenotecnum incognitum in copula and those of uncopulated male and female of Trichadenotecnum pseudomedium. By comparing the changes in male and female genital structures and related muscles in copulated and uncopulated states, the function of each genital structure can be described. During the copulation, we found that the female subgenital plate was hooked into the male body by the distal process on the male paraproct and was fixed by the male epiproct, hypandrium and phallosome. In addition, sexual coevolution was suggested by tightly contacting structures, that is, thorny male hypandrium and thickened membrane around the female spermapore plate. These results not only give us a new understanding copulation process of Trichadenotecnum, but also explain the reasons why genital structures are so divers in the genus.
尽管在先前的研究中已经描述了树虱属Trichadenotecnum巨大的生殖器多样性，但是在交配过程中生殖器结构的具体功能却较少受到研究关注。我们重建了交配中的未知树虱Trichadenotecnum incognitum以及未交配的拟中树虱Trichadenotecnum pseudomedium的雄性和雌性生殖器各结构的三维模型。通过比较交配状态和未交配状态下雄性和雌性生殖器结构及相关肌肉的变化，可以描述每个生殖器结构的功能。在交配过程中，我们发现雌性亚生殖板被雄性肛侧突上的远端突起钩入雄性体内，并由雄性肛上板、下生殖板和阳茎固定。此外，通过紧密接触的结构表明存在性协同进化，即雄性有刺的下生殖板和雌性受精孔板周围增厚的膜。这些结果不仅让我们对树虱属的交配过程有了新的认识，也解释了该属生殖器结构为何如此多样的原因。
