A comparative analysis of female genitalia of seven Old World snake species using a silicone modeling technique

Genitalia diversity has long been an object of evolutionary and functional morphology studies, with a primary focus on male copulatory organs. Despite extensive studies on snake genitalia, particularly hemipenes, female copulatory organs remain understudied. This research aims to fill this gap by modifying a recently introduced silicone modeling methodology for preparation and by describing female snake genitalia for seven previously undescribed species. The methodology is based on employing a two-component condensation silicone into snakes’ genitalia to create internal models for intersexual comparative morphology. We conducted a comprehensive examination of seven Old World snake species – Boidae: Eryx jaculus, Colubridae: Dolichophis caspius, Zamenis longissimus, Elaphe quatuorlineata, Coronella austriaca, and Viperidae: Vipera ammodytes, and V. berus. Our results reveal significant variations in female genitalia morphology and we speculate that this is also reflected in copulation adjustment between the different types of species’ genitalia.