Tyrannobdella rex, which means tyrant leech king, is less than two inches long and lives in the remote parts of the Upper Amazon.
It has 8 large teeth lining a single jaw and was discovered three years ago in Perú when a 44.5mm leech was plucked from the nose of a girl who had recently been bathing in a river.
Although there are 600 to 700 species of described leeches, it is thought that there could be as many as 10,000 species throughout the world in marine, terrestrial and fresh water environments.
This species is most closely related to Pintobdella chiapasensis, a leech from Chiapas in Mexico that is typically hosted by tapir but also infests cows.
It is from the leech family Praobdellidae, found in Mexico, Africa, and the Middle East, all of which share this feeding behavior and which can pose a risk to human health in certain parts of the world.
Mark Siddall, curator in the Division of Invertebrate Zoology at the American Museum of Natural History, said: "The earliest species in this family of these leeches no-doubt shared an environment with dinosaurs about 200 million years ago when some ancestor of our T. rex may have been up that other T. rex's nose."
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