The ultrastructure of the spermatheca of Mordellistena brevicauda (Coleoptera, Tenebrionoidea) and the associated bacterial cells

Romano Dallai; David Mercati; Pietro Lupetti

doi:10.1016/j.asd.2024.101357

The ultrastructure of the spermatheca of Mordellistena brevicauda (Coleoptera, Tenebrionoidea) and the associated bacterial cells

Arthropod Struct Dev. 2024 Apr 25:80:101357. doi: 10.1016/j.asd.2024.101357. Online ahead of print.

Authors

Romano Dallai¹, David Mercati², Pietro Lupetti³

Affiliations

¹ Department of Life Sciences, University of Siena, Siena, Italy. Electronic address: romano.dallai@unisi.it.
² Department of Life Sciences, University of Siena, Siena, Italy. Electronic address: david.mercati@unisi.it.
³ Department of Life Sciences, University of Siena, Siena, Italy. Electronic address: pietro.lupetti@unisi.it.

PMID: 38669939
DOI: 10.1016/j.asd.2024.101357

Abstract

The ultrastructural study on the female reproductive system of the beetle M. brevicauda (Mordellidae) confirmed the positive correlation between the length of the sperm and the size of the female seminal receptacle (Spermatheca). The spermatheca of the species is characterized by an apical bulb-like structure where the spermathecal duct forms numerous folds filled with sperm. At this level many bacterial cells are present intermingled with the duct folds. Some are organized in large structures, such as bacteriomes, while other are single bacteriocytes. The latter are often found near the basal lamina of duct epithelium. In addition, some bacteria are visible in the cytoplasm of the duct epithelial cells. Interestingly, bacterial cells have never been observed in the duct lumen. The possible function of the bacterial cells is discussed.

Keywords: Coevolution of reproductive systems; Insect reproduction; Spermatheca ultrastructure.