Interspecific Variability of the External Female Genital Mutilation Rate and Its Relationship with Female Aggression and Sexual Cannibalism in Cyclosa Spiders

External female genital mutilation (EFGM) is the strategy employed by male spiders to ensure paternity during sexual conflict over female remating. Three orb-web spider species have been identified to engage in EFGM, wherein males remove the female’s genital scape, which is crucial for successful genital coupling. Mutilated females lose their remating ability. Despite the apparent fitness advantage of mutilator males over non-mutilators, mutilation success rates vary across these species. The extent to which females engage in aggression and sexual cannibalism as potential countermeasures against EFGM is also variable. In this study, two consecutive staged matings were conducted in Cyclosa confusa and C. vallata spiders to determine the rate of successful mutilation and the influence of sexual cannibalism and female aggression. Both species exhibited low rates of sexual cannibalism and female aggression. While most matings involving unmated C. vallata females resulted in successful mutilation, one-third of C. confusa females retained an intact scape after mating. Additionally, mutilation rates in C. confusa increased with male size and weight and decreased with female weight. In contrast to previous studies on other species, our results revealed low mutilation success with low sexual cannibalism and female aggression in C. confusa.