At first glance, the Indian valve turtle does not seem particularly noticeable in this photo. From an anatomical point of view, it cannot be distinguished from its conspecifics, but: its golden color makes it a rarity. The reason for this coloring is a genetic defect.
The Indian soft shell turtle (Lissemys punctata) occurs in South Asian regions such as India, Nepal and Sri Lanka. Mostly it can be found in trenches, lakes and in standing water or in rice fields. Due to its greenish-gray color and the yellow spots on the head and neck, it is well camouflaged in the murky water. It owes its name to the flap-like protrusions on the plastron, its belly shell, which protect its legs. Valve turtles are omnivores: they feed on leaves and flowers to snails, fish and frogs.
In Nepal, in the municipality of Dhanushadham, a villager discovered a turtle with an unusually gold-colored shell on April 14, 2018. In July 2020, the research group under Hinrich Kaiser from the Zoological Research Museum in Bonn and his colleague Kamal Devkota from Nepal learned of the existence of another gold-colored turtle in the Indian state of Odisha. According to the researchers, this is an Indian soft shell turtle, which has a coloring that is very rare in nature. “The lack of body pigmentation makes the turtle appear gold in color, with only the eyes showing dark pigmentation,” says Devkota. To find out the cause of this rarity, the research team examined the genome of the turtle.
The first assumption was that it could be albinism. Here the animal lacks the entire pigmentation in skin and hair, the eyes are usually red in color. The cause is the missing enzyme tyrosinase, which is involved in the production of the skin pigment melanin. Researchers estimate that around 1 in 10,000 mammals are affected by this phenomenon. However, examination of the turtle refuted this assumption. Instead, it is an extremely rare genetic defect. In the turtle found, the pigmentation is reduced due to a lack of melanin, so that the striking gold coloration occurs on the body. Amazingly, the eyes of the animals are normal colored.
The researchers speak of the rare “chromatic leukism”. It is only “the fifth documented observation of the kind,” says Devokta. Their color is an acute danger for the turtle. Because of its light golden color, it cannot camouflage itself in the water and is therefore unprotected. The researchers also fear that the special coloring will make them a popular catch for animal dealers.
The illegal keeping of turtles as pets is a national problem in Nepal. Medical professionals also often use them as a remedy: eating turtles and their eggs is said to promise improved health, longevity and masculinity.
In addition, organizations in Nepal warn that the decline in wetlands, unsustainable methods of fishing and excessive use of chemicals in agriculture are also having a negative impact on turtle populations. Four of the 16 turtle species native to Nepal are already threatened with extinction.