In the warm and humid silence of one Thai forestresearchers of theChulalongkorn University They were digging between the earth and the roots when they found themselves in front of a small two -tone body. On the one hand white, on the other, orange lively: a contrast so clear that it seems painted. It was a spider never seen before, belonging to the genre Damarchusbut with a peculiarity that made it unique: half male and half female. This discovery, just published in the magazine Zootoxa from Kunsete and colleagues, represents the First case of ginandromorphism (a single body half male and half female) never recorded in the family Bemmeridae and led to the definition of a new species, Damarchus Inazuma sp. Nov. In fact, the male and female of the new species are also described in the same study. The research, born from field observations and morphological analysis conducted with high resolution microscopes and photographs, combines taxonomy and development biology, opening a window on a phenomenon still little included in primitive spiders. The name inzuma (which in Japanese means “lightning”) is a tribute to a manga character One Piece capable of change sex: a perfect reference for a spider that contains both sexes in the same body.
What are the bemmeridae spiders and why they are known
THE Bemmeridae they are spiders belonging to the subrdine of migalomorphsdistant relatives of the best known Tarantolids (who include the Tarantole). Include only four genres – Athmetrochlus, Damarchus, Homostola and Spinttenus – And they are mainly found between southern Africa and tropical Asia.
So far the genus Damarchus had nine known species, distributed between India, Malaysia, Myanmar and Thailand, but scholars had been suspected for some time that many others could exist. Thai researchers collected the specimens in 2019 and 2021 in Nong Rong in Phanom Thuan. The lairs were dug in the groundin areas it is disturbed by human activity is protected within the forest. After the collection, the samples were kept in 95% in ethanol and then analyzed with microscopes.
Characteristics of the new species Damarchus Inazuma
The male Of Damarchus Inazuma measures 17 millimeters, with body covered with one whitish patina and robust legs. It stands out from the related species for Three tips On the “tibia” of the first paw and a part of the copulator bulb, called “Embolus”, long and curved. There femaleon the other hand, is bigger – about 23 millimeters – and of Live orange colorwith spermathe (the organs that in the females of the species act as bags in which the sperm for fertilization are welcomed) elongated and curved inwards. Both sexes present four supply chains (the organs that produce silk) and a characteristic “combing” of thorns on the rear legs, useful for cleaning the silk. The authors, however, underline that the classification of the group is still uncertain and that will serve molecular studies to confirm its evolutionary position.
The Ginandromorph spider half male and half a female: the study
The real protagonist of the study, however, is a unique individual: a bilateral ginandromorph. A body split in half: the right side of the body shows male strokes – thinner legs, light coloring, nail teeth arranged in a row in the shape of S – while the left side is feminineorange, with spermateche developed only that side. The body measures 24.67 mm and even the eye size and the chelylicre (the appendices that form the puppeteers of the spider’s mouth) vary between the two sides: the right and left chelyrs are respectively 3.0 mm and 4.05 mm long.
This type of asymmetry, which combines male and female structures, is extremely rare in migalomorphic spiders. In the araneomorphic species (the most common ones, such as weaving spiders) it is estimated that it occurs in about 1 individual out of 17,000. In the migalomorphs, however, they had been documented Only two cases before this: one in 2017 (Pterinochilus Murinus) and one in 2020 (Theraphosa Blondi).
Ginandromorphism, explain Kunsete and colleagues, can derive from chromosomal anomalies, Like the loss of sex chromosomes during the formation of zygote. Sometimes it can be induced by infections or other natural stress. The result is an organism that, during embryonic development, “chooses” two different sexual paths on the two sides of the body. In the case of Damarchus Inazumathe male and female side are clearly divided, Making the specimen a perfect model to study how sexual differences develop in spiders.
