Recently, we reported the most masculine females ever discovered (Yoshizawa et al. 2014). In the Brazilian cave insect genusNeotrogla (Insecta: Psocodea: 'Psocoptera': Prionoglarididae), females have a highly elaborate penis-like organ, termed a gynosome, whereas the males have a simple vagina-like genital chamber. Furthermore, the female penis has species-specific elaborations such as numerous spines, by which a female anchors to a male during a long copulation (30-70 hours!) to receive a nutritious seminal gift. The male vagina possesses species-specific pouches that accept the spines on the female penis. This is the first definite discovery of a female intromittent organ in the animal kingdom and also the first detection of reversed genital coevolution.