The sclerite composition of the female genitalic region in an enigmatic silverfish Tricholepidion gertschi (Insecta, Zygentoma)

• Published in: Zoodiversity (Vestnik Zoologii)
• Date: 2026
• Volume: 60
• Issue: 4
• ISSN: 2707-7268
• Author Affiliations: N. Matushkina — Department of Ecology and Zoology, Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, Ukraine
• Main Author: Matushkina, N.
• Format: Article
• Language: English
• Published: Publishing House "Akademperiodyka" of the National Academy of Sciences of Ukraine 2026
• Online Access: https://ojs.akademperiodyka.org.ua/index.php/Zoodiversity/article/view/875
• Journal Title: Zoodiversity

Tricholepidion gertschi (Lepidotrichidae) has an unresolved phylogenetic position, being placed as sister group to Dicondylia (Zygentoma + Pterygota) or within Zygentoma, making it the only insect species whose ordinal status remains uncertain. In this work, the sclerite composition of the female postabdomen of T. gertschi was investigated using scanning electron microscopy. A transverse sclerotized bridge between the gonangula, interpreted as a derivative of sternite 9, was found. Comparative analysis with published data shows that the presence of distinct sternal sclerotisations in segments 8 and 9 of T. gertschi is a plesiomorphic condition that has not been found in Zygentoma so far. This finding confirms the unique morphology of this species. It is suggested that transverse sternal sclerotisations in T. gertschi enhance mechanical stabilisation of the ovipositor during egg laying in hard substrates such as wood.