Fine structure of the female genital system of diving beetle Stictonectes optatus (Seidlitz, 1887) (Dytiscidae-Hydroporinae) and evidence of mating plug formation

• Published in: Arthropod structure & development 2023-03, Vol.73, p.101250-101250, Article 101250
• Main Authors: Dallai, Romano, Mercati, David, Fanciulli, Pietro Paolo, Lupetti, Pietro
• Format: Article
• Language: English
• Subjects: Animals; Coleoptera; Diving beetle reproduction; Female; Female genital system; Genitalia, Female; Male; Mating plug formation; Reproduction; Semen; Spermatozoa
• ISSN: 1467-8039; 1873-5495
• DOI: 10.1016/j.asd.2023.101250

The general organization of the female genital system of the diving beetle Stictonectes optatus was studied, clarifying the complex structure of the spermatheca and spermathecal gland. The two structures adhere closely to each other, sharing a small area of their cuticular epithelium. A long duct connects the bursa copulatrix to the spermatheca, where the sperm are stored. The sperm reach the common oviduct, where egg fertilization occurs, via a fertilization duct. The spermathecal gland cells have extracellular cisterns where secretions are stored. Thin ducts composed of duct-forming cells transport these secretions to the apical gland region and into the spermathecal lumen. Soon after mating, the bursa copulatrix is almost completely occupied by a plug secreted by the male accessory glands. The secretions of the bursa epithelium seem to contribute to plug formation. Later this plug becomes large and spherical, obstructing the bursa copulatrix. •The spermatheca and the spermathecal gland are independent but closely connected organs.•A short fertilization duct opens into the common oviduct.•After mating, the bursa copulatrix is occupied by a large spherical mating plug.•The secretions of the bursa epithelium may contribute to plug formation.