ⓘ Neotrogla

                                     

ⓘ Neotrogla

Neotrogla are about the size of fleas. The genus can be distinguished from other genera of Speleketorinae by the presence of articulated spines on the anterior side of their legs, and by their unique genitalia. Both sexes have hairs on their tarsus, but the hairs on females are markedly longer. Neotrogla have branched hindwings and brown forewings.

Female Neotrogla possess a penis-like organ, incorrectly called gynosome ", but interchangeably referred to penis. They aggressively seek out mates, while males are more selective. During mating, the female collects the male and penetrates his small genital opening from behind. Her gynosome swells and tiny barbs on the organ lock the individuals tightly together when a researcher tried to separate mating individuals the male was torn in two, leaving his reproductive organs attached to the female. During mating, the female uses her gynosome to retrieve sperm and nutrients to the seminal fluid of the male. One mating session can last from 40 to 70 hours.

The restoration of the genital organs may be due to the lack of nutrients in the environment of the cave, which makes it evolutionarily useful for the female to extract nutrients from the male. Female Neotrogla drain males of seminal fluid even when they are too young to reproduce, giving weight to this theory, according to entomologist Kazunori also Yoshizawa who co-authored the first studies of insect mating behavior. If men spend most of their limited resources to produce such nutrient-rich liquid, it would also help to explain why men carefully choose their partners. Males of other insects are known to produce similar "nuptial gifts" of nutrients to be transferred during mating. However, the evolutionary origin of the penis-like organ remains a complete mystery. "Usually a new structure evolves as the change of the previously existing structure," said Yoshizawa. Such adaptation would be "extremely difficult" because of the need for both male and female genital organs, changes in the structures at the same time.

Penetration men women, known in some species such as the seahorse, but only Neotrogla females have a well-defined organ that can be described as penis. In addition, the reversal of sex roles has been recorded in several other species. Neotrogla, however, appears to be unique as traits. According to Yoshizawa, the animal offers a unique opportunity to study the conflict between the sexes and the role of sexual selection in evolution. "It is important to unveil why, among many sex-role-the reverse of animals, only Neotrogla evolved developed female penis", he said. In 2017, Kazunori also Yoshizawa, Rodrigo Ferreira Yoshitaka Kamimura Charles Lienhard was awarded the IG Nobel prize in biology "for their discovery of the female penis and male vagina, in cave insects".