Scientists in Thailand have identified a new species of spider that displays both male and female physical traits, marking a rare biological phenomenon known as gynandromorphism. The discovery, which includes a single intersex specimen among several collected, offers fresh insight into arachnid development and sexual differentiation.
Researchers described the find as the first known case of a gynandromorph within the spider family Bemmeridae.
The unusual specimen was part of a group of spiders discovered near a forested area in Nong Rong, located in the Phanom Thuan district of Kanchanaburi province in western Thailand. Local residents submitted the samples to experts at the Chulalongkorn University Museum of Natural History for examination.
In a study published in the peer-reviewed journal Zootaxa, researchers explained that the intersex spider showed a clear division between male and female characteristics. The right side of its body exhibited traits typical of males, while the left side resembled a female—an exact bilateral split.
The striking appearance, with orange on one side and white on the other, closely mirrors sexual dimorphism in the species. Females are typically orange, and males appear grayish white.
Color pattern and naming inspired by Japanese manga character
The research team named the species after Inazuma, a character from the Japanese manga One Piece, who is known for switching between male and female forms.
Lead researcher Narin Chomphuphuang said the character’s color scheme and gender-shifting nature reflected the unique biological features seen in the specimen.
Gynandromorphism is different from hermaphroditism. While hermaphroditic animals possess both reproductive organs and remain symmetrical, gynandromorphs show distinct male and female traits split along the body.
The study mentions that only two prior cases of gynandromorph spiders have been documented, both from the Theraphosidae family. This case represents the first such record in the Bemmeridae family, which includes the genus Damarchus.
The new species appears to belong to this genus, known for burrowing spiders found in South and Southeast Asia. These spiders build Y-shaped burrows in the ground and ambush prey from their concealed tunnels. However, researchers noted that molecular data is still needed to confirm the exact classification.
Physical differences between sexes and possible genetic cause
The male of the species measures about 0.6 inches and has a grayish tone, often covered in an unidentified white substance that turns reddish-brown when preserved. Females are larger, around one inch long, and are bright orange without the white coating.
Researchers said the cause of gynandromorphism in this case remains unclear. Referencing earlier work by arachnologist Benjamin Kaston, they suggested it may be linked to the loss of sexual X chromosomes during early development, potentially triggered by natural factors like parasitic infections.
The identification of a new species of intersex spider in Thailand marks a rare and significant development in the study of arachnids, adding to the limited number of documented gynandromorphs worldwide.
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