Why Did a Female Penis Evolve in a Small Group of Cave Insects?

Kazunori Yoshizawa, Rodrigo L. Ferreira, Charles Lienhard, Yoshitaka Kamimura

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The evolution of a female penis is an extremely rare event and is only known to have occurred in a tribe of small cave insects, Sensitibillini (Psocodea: Trogiomorpha: Prionoglarididae). The female penis, which is protrudable and inserted into the male vagina-like cavity during copulation to receive semen, is thought to have evolved independently twice in this tribe, in the Brazilian Neotrogla and the African Afrotrogla. These findings strongly suggest that there are some factors unique to Sensitibillini that have facilitated female penis evolution. Here, several hypothetical factors are presented that may have enabled the evolution of the female penis in Sensitibillini. The female–female competition for nutritious semen, the oligotrophic environment, and the twin insemination slots with switching valve are considered to be the driving factors for female penis evolution. Additionally, the following factors are considered responsible for relaxing the constraint against female penis evolution: preexistence of the female-above mating position, the elongated duct connecting the female pre-penis with the sperm storage organ, and the small male genital cavity accepting the female genital tubercle bearing the opening of this duct. Understanding the factors enabling female penis evolution may also shed light on the evolution of the male penis.

Original languageEnglish
Article number1900005
Issue number6
Publication statusPublished - 2019 Jun


  • Afrotrogla
  • Neotrogla
  • Sensitibillini
  • genital evolution
  • sex-role reversal
  • sexual selection

ASJC Scopus subject areas

  • General Biochemistry,Genetics and Molecular Biology


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