US researchers have found a tiny threadlike millipede recognised as the evolutionary cousin of the leggiest animal on the planet, Illacme plenipes.The enigmatic millipede, named Illacme tobini after cave biologist Ben Tobin of the National Park Service, was discovered along with many spiders, pseudoscorpions, and flies in the unexplored dark marble caves in Sequoia National Park in California.According to diplopodologists, the new species may possess "only" 414 legs, compared to its relative's 750, yet, it has a similar complement of bizarre anatomical features, including a body armed with 200 poison glands, silk-secreting hairs, and four penises. "I never would have expected that a second species of the leggiest animal on the planet would be discovered in a cave 150 miles away," said Paul Marek, Assistant Professor at Virginia Polytechnic Institute and State University, in the US. In addition to the new millipede's legginess, it also has bizarre-looking mouthparts of a mysterious function, four legs that are modified into penises, a body covered in long silk-secreting hairs, and paired nozzles on each of its over 100 segments that squirt a defence chemical of an unknown nature, the researchers stated.Its closest relative lives under giant sandstone boulders outside of San Juan Bautista, California.The findings were published in the journal ZooKeys.