On the edge of Thai forests, an astonishing creature has been discovered, defying traditional biological classifications. This spider named
Damarchus inazuma indeed exhibits a perfect bodily division between the male and female characteristics of its species.
This remarkable discovery provides a rare example of bilateral gynandromorphism in burrowing spiders. Researchers from Chulalongkorn University, having examined specimens collected in Kanchanaburi province, found that this morphological singularity is accompanied by very marked sexual differences within the species.
Pronounced sexual dimorphism
In this species, males and females are clearly distinguished by their size and coloration, which makes the appearance of the discovered gynandromorph specimen (possessing characteristics of both sexes) all the more striking. The males, measuring approximately 1.5 centimeters (0.6 inches), display a gray hue over their entire body, which is completely covered with a white substance whose exact nature remains undetermined to this day.
The females, substantially larger at 2.5 centimeters (1 inch), exhibit a brown-reddish coloration on their body and legs, while their abdomen adopts an anthracite gray hue. Unlike males, they lack this white layer that so intrigues scientists.
During handling, the species displays notable defensive behaviors, with specimens not hesitating to deploy their chelicerae with some aggressiveness. Researchers have even observed the occasional appearance of liquid droplets at the tip of their mouth appendages, suggesting the possible presence of venom.
An exceptional biological phenomenon
The gynandromorph specimen exhibits a perfect bilateral division between the two sexual characteristics, as if two distinct spiders had merged into one. Its left half shows the typical orange coloration of females, while its right half retains the gray and white appearance characteristic of males.
This morphological division earned it its name,
Damarchus inazuma, inspired by a character from the manga One Piece who has the ability to change sex. Researchers also emphasize in
Zootaxa the aesthetic correspondence between the specimen and the character Inazuma, whose bilateral chromatic asymmetry shows striking similarities with that of the spider.
Gynandromorphism would result from chromosomal abnormalities occurring during the early stages of embryonic development, according to the hypothesis favored by scientists. These disturbances could stem from various environmental or parasitic factors, although the exact mechanisms remain to be fully elucidated.
To go further: What is gynandromorphism?
Gynandromorphism refers to the simultaneous presence of male and female characteristics in the same individual, a phenomenon that has long intrigued biologists. This condition manifests through an often asymmetric distribution of secondary sexual traits, unlike hermaphroditism which exhibits bilateral symmetry. It concerns various animal species, particularly arthropods and birds, where observations are most documented.
This phenomenon, distinct from hermaphroditism, involves a clearly divided bodily distribution between the characteristics of both sexes. Each side fully expresses the attributes of a different sex, creating this impression of dual morphological identity. The demarcation line between the male and female parts is often perfectly visible, as in the case of this Thai spider.
The origin of gynandromorphism would date back to abnormalities occurring during the first cell divisions of the embryo. The loss of sex chromosomes during embryonic development would be the main cause, according to the most recent research. External factors such as parasitic or viral infections could also play a role in triggering this exceptional process.
Article author: Cédric DEPOND