US biologists say they've discovered a new species of scorpion in mountains in southern Arizona that are within sight of metropolitan Tucson. The new species, Vaejovis brysoni, was found in the Santa Catalina Mountains overlooking the city, they said in a report published in the journal Zookeys. For more than 50 years only four species of mountain scorpions were known from the state of Arizona, but that number has more than doubled over the past six years, the researchers said. Arizona is known for isolated mountain habitats scattered across the desert, known as Sky Islands. These Sky Islands are where new species are still being discovered, scientists said. "This latest new scorpion is a prime example of the amazing diversity of life still to be discovered, right here in 21st century America," Richard F. Ayrey, one of the co-author of the Zookeys article, said.