This study deals with the abdomen and genitalia of the female Scarabaeoidea. The first part describes genital segment and ectodermic genitalia organization. It is complemented by a bibliographic study allowing us to make a nomenclatural revision and a detailed study of 112 species belonging to the different families of the Scarabaeoidea. For each species, abdominal type, terminalia and genital ducts are described and illustrated. The second part is an analysis of genital segments and their evolution throughout the Scarabaeoidea. Segments VIII and IX are defined as made of one tergite, two epipleurites and two monomeric gonopods (Ochodaeidae, Trogidae). In most cases, segmental organization is modified by different simplifying processes: reduction process leading to residual hemisclerites such as dorsopleurites and ventropleurites IX; fusion process leading to coxosubcoxites IX; internalization process explaining the presence of secondary sclerotinisations on the opening of the genital ducts. The second part also describes internal genitalia which are primitively made of oviduct and vagina connected on its dorsal side with a large bursa copulatrix and a membraneous seminal receptacle. Important modifications are found in Geotrupidae, Aphodiidae, Aegialiidae and Scarabaeidae and relate to a decreasing fecundity: disappearance of bursa copulatrix; curvation and sclerotinisation of spermatheca; decrease of spermathecal gland size. These modifications justify setting aside those four families in a monophyletic clade, clearly different from others in Scarabaeoidea.
Insecta, Coleoptera, Scarabaeoidea, abdomen, genitalia, females, morphology.