Spider With a Venomous Bite That Rots Human Flesh Discovered in Mexico

Researchers in Mexico have identified a new species of spider with venom that is capable of rotting human flesh.

A team from the National Autonomous University of Mexico (UNAM) found the spider, dubbed Loxosceles tenochtitlan, in the Valley of Mexico—a highland plateau in the center of the country where Mexico City is located.

The spider was named after Tenochtitlan, the ancient capital city of the Aztec Empire.

The arachnid belongs to a genus, or group of species, known as Loxosceles—which are commonly referred to as recluse spiders, violin spiders, brown spiders, fiddle-backs or reapers. They are known for their venomous bites which, while not fatal, can cause necrosis in the skin, leaving a permanent scar.

According to the UNAM team, Mexico has the highest diversity of Loxosceles spiders in the world being home to around 40 of the 140 known species. The researchers say the newly identified species is the first that's considered native to the Valley of Mexico region.

The team led by Alejandro Valdez-Mondragón from UNAM's Institute of Biology said that there were already records of Loxosceles tenochtitlan—although scientists had previously assumed that these specimens represented the already-known species Loxosceles misteca. This species is native to the the Mexican states of Morelos and Guerrero, although it has been introduced into the Valley of Mexico.

"As [Loxosceles tenochtitlan] is morphologically similar to [Loxosceles misteca,] it was initially thought that it had been introduced to this region by the shipping of ornamental plants. But when doing molecular biology studies of both species, we realized that they are completely different," Valdez-Mondragón said in a statement.

According to the team, the main differences can be seen in the male spider's palps—an organ of touch in arachnids—and the sexual organs of the female. L. tenochtitlan also has a distinct look in comparison to L. misteca.

venomous spider, Loxosceles tenochtitlan
The newly identified spider Loxosceles tenochtitlan. UNAM

"At first glance [L. tenochtitlan] can be identified because its dark brown color is not striking, and, unlike other species in the country, it has a dorsal pattern in the form of a very visible violin, hence its name," Valdez-Mondragón.

The researchers said that these spiders generally try to avoid contact with humans, but they may bite in defence if they feel threatened.

In urban areas, the spiders tend to live in places like warehouses or in trash—which attracts insects that they eat, such as cockroaches, flies and mealybugs. They can also be found in homes, where they may hide among clothes, furniture or in walls.

"We provide them with the temperature, humidity and food so that they are established in our homes, which puts us at risk of having an accident with them, although feeding on insects also performs an important ecological function," Valdez-Mondragon said.