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article imageFemale sports penis in sex-reversed newly discovered species

By Robert Myles     Apr 18, 2014 in Science
Lavras - Researchers have discovered little-known cave insects in Brazil with odd sexual habits. The troglodyte species has sex-reversed genitalia, the female sporting an elaborate spiked penis that penetrates an opening like a vagina in her male consort.
The Brazilian insects represent four distinct but related species in the genus Neotrogla. In a world of weird and wonderful ways that animals find to copulate, they’re the first to be confirmed where the physical sexual organs are reversed. As Science Recorder reports, they may be unique since it appears the males may be the choosers while females take on an aggressive role. Not only that, the female has impressive staying power. When copulation between females and males of the species starts, it can go on for days at a time.
But this possibly unique species might have gone completely unnoticed. Almost 20 years ago, Rodrigo Ferreira, a cave ecologist the Federal University of Lavras, Brazil, discovered cave dwelling insects during an expedition, reports Smithsonian. The young age of specimens found by Ferreira meant that identification wasn’t possible.
It was only after Ferreira sent off specimens to insect specialist Charles Lienhard in Geneva that analysis started to get really interesting. It was Lienhard who recognized them as a new genus and also discovered the females' very impressive penis-like organs.
The females were found to have an internal penis-like organ that only extended during mating while males had a pouch-like vagina.
The species examined was like nothing else in the larger family of cave insects and the researchers knew they were seeing a completely new genus with reversed sex organs.
Co-author of the new study, Kazunori Yoshizawa, an entomologist at Hokkaido University in Japan, commented on the unique finding, "Although sex-role reversal has been identified in several different animals, Neotrogla is the only example in which the intromittent organ is also reversed."
Staying power
The species copulates by means of the female inserting an elaborate penis-like organ into males' much-reduced, vagina-like opening. The act of copulation can last an impressive 40 to 70 hours. And just like heterosexual human social conventions, it’s the male that’s the bearer of gifts given to the female in the shape of nutritious seminal globs in addition to the male sperm. That seems to increase females’ libido, making it advantageous for females to mate at a higher rate.
Newly discovered cave-dweling insects from brazil Neotrogla curvata in the act of copulation.
Newly discovered cave-dweling insects from brazil Neotrogla curvata in the act of copulation.
Permision Current Biology, Yoshizawa et al.
In all four of the Neotrogla species, the scientists found that the females’ penis-like structure, called the gynosome, is inserted into males then used to receive generous capsules of nourishment and sperm. Once inside a male, the membranous part of the female gynosome inflates and is then anchored inside the male by numerous spiky spines.
Till death us do not part
So taut becomes the bonding that one time, when researchers tried to pull a copulating male and female apart, the male’s abdomen was ripped from its thorax without breaking the genital coupling.
The researchers theorize that the resource-poor cave environment may be the driving force behind the species’ sex organs and sex-role reversal. Ferreira thinks hunger could be the reason the female Neotrogla not only spears the male but anchors herself there for hours on end sufficient for the female to receive as much nourishment to sate her desires from the male’s spermous side order.
The insects will now be studied in an effort to better understand what makes them so special. According to the researchers Neotrogla offers a range of opportunities to test ideas about sexual selection, conflict between the sexes, and the evolution of novelty.
The research is published this week in Current Biology under the title Female Penis, Male Vagina, and Their Correlated Evolution in a Cave Insect - authors, Kazunori Yoshizawa, Rodrigo L. Ferreira, Yoshitaka Kamimura and Charles Lienhard.
More about Insects, New species, neotrogla, insect with female penis, male vagina
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