Acquisition of novel muscles enabled protruding and retracting mechanisms of female penis in sex-role reversed cave insects. Issue 1 (11th January 2023)

• Record Type: Journal Article
• Authors: Cheng, Zixin; Kamimura, Yoshitaka; Ferreira, Rodrigo L.; Lienhard, Charles; Yoshizawa, Kazunori
• Is Part Of: Royal Society open science. Volume 10:Issue 1(2023)
• Publication Date: 2023-01-11
• Subjects: female genitalia -- gynosome -- homology -- Neotrogla -- muscle; Science -- Periodicals; 500
• DOI: 10.1098/rsos.220471
• Languages: English
• ISSNs: 2054-5703

Abstract

Abstract : Brazilian sex-role reversed cave insects (genus Neotrogla ) have a striking structure called the gynosome (or female penis), which deeply penetrates male vagina-like genitalia during copulation to receive nutritious semen. However, the protruding and retracting mechanisms of the female penis, including their evolutionary origin, are poorly understood. By using micro-computed tomography (µCT), we compared the genital morphology and musculature between species with a gynosome and others lacking this structure. As a result, we discovered two groups of muscles related to the protrusion and retraction of gynosomes. These muscles were also observed in species with non-protrusible prepenis. This suggests that evolution of these muscles preceded the acquisition of the protruding function of the gynosome, originally having a putative stimulatory function to receive nutritious semen. This intermediate stage probably allowed for the reversal of genital functions.