Sexual selection has been curious with this species of insects discovered in Brazilian caves , since they represent the first example of an animal whose individuals have the genitalia of the opposite sex, that is, the female is the one with a penis and the male with the vagina. .
Scientists have found a group of four species of the genus Neotrogla (within the order of the so-called “book lice”) that, among their sexual peculiarities, have the ability to copulate for 70 hours without interruption .
The curious insects, presented in the journal Current Biology , barely measure between 2.7 and 3.7 millimeters and present this curious sexual combination: “By having a penis, Neotrogla females appear to be male, except because they produce eggs and have related structures. with the laying of eggs. The females of this genus are probably the most masculine among all the animals discovered to date, ”explains Kazunori Yoshizawa, leader of the study.
The genitalia of these insects are also quite striking. The female’s penis has several spines with which it grips the male with force during copulation. The male, for his part, places himself under the female, allowing the latter to insert his penis into the male’s vagina so that he can leave his sperm. The presence of these spines, according to experts, could have more of an anchoring function than a genital stimulator.
“ It is very likely that the entire mating process is actively controlled by the females , while the males are rather passive. The female penis, having this anchoring function, is an ideal device for actively controlling intercourse ”, explains Kazunori.





