New Species Of Spider With Flesh-Eating Venom Found In Mexico


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist


Loxosceles tenochtitlan was found by Alejandro Valdez-Mondragón, an academic at the Institute of Biology, and four of his students. National Autonomous University of Mexico

A genus of spider famed and feared for its flesh-eating venom has got a new gang member. 

A group of college students and their professor from the National Autonomous University of Mexico (UNAM) recently discovered the new species of violin spider in the Valley of Mexico, a mountainous and volcanic plateau in central Mexico. 


Dubbed Loxosceles tenochtitlan, its name is a homage to the ancient capital of the Aztec empire, the city of Tenochtitlan. The Loxosceles genus members are also known as violin spiders or fiddle-backs due to the violin-shaped pattern often found on their back. Out of the 140 species of this genus that exist in the world, Mexico is home to at least 40. 

"At first glance, it 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," explained Alejandro Valdez-Mondragón, professor at the Tlaxcala headquarters of the Institute of Biology at UNAM, who was part of the discovery. 

The bite of a violin spider is not fatal but it is nasty, and will most likely require medical attention. It starts with a relatively painless sore that turns purple and pink. As the team note, it can easily be confused with a skin infection. However, many Loxosceles spiders have potent tissue-destroying venoms that can rot human flesh, a process scientifically known as necrosis. The toxin varies in concentration from species to species, but it’s suspected that most (if not all) species of the genus Loxosceles have necrotic venom.

The condition, sometimes called Loxoscelism, is characterized by a necrotic wound at the site of bite that can persist for a couple of months. Serious illness and death are rare, although a bite can sometimes result in necrotized flesh that may require plastic surgery to repair. 


“The critical stage is the first 24 hours, and sometimes up to 48 hours when you begin to see the effects. The reaction begins with a sore that expands and produces quite considerable tissue necrosis (or death of tissue),” Valdez-Mondragón told the Yucatan Times, a local Mexican newspaper, earlier this year. 

Violin spiders can often be found in areas shared by humans, such as dusty basements or warehouses, that contain lots of cracks to hide in and hunt from. However, if there’s any good news, it’s that this genus tends to avoid human contact, hence its other name: the recluse spider. Shy as they may be, some recent studies have suggested North America could be seeing more of this spider, most notably Loxosceles reclusa, as a result of warming temperatures from climate change. 


  • tag
  • spider,

  • venom,

  • flesh-eating,

  • Mexico,

  • violin spider,

  • Loxosceles tenochtitlan,

  • Loxosceles