For a long time, small spotted cats across much of South America were filed under one label: the tiger cat, or Leopardus tigrinus. Biologists had argued for years about how many kinds were hiding under that label, because tiger cats are shy, live in forests, and look a lot alike in photos and museum drawers.
The Bolivian thread of the story started with live animals. Biologists working with Bolivia's felid research program saw a captive tiger cat whose rosettes were larger and more irregular than they expected. The study's type specimen is an adult male that was live captured in September 2021 near the village of Arapata, in the Nor Yungas province of La Paz, at about 1,570 meters above sea level, and that lives in captivity.
To settle the question, an international team led by Jonas Lescroart, Paola Nogales-Ascarrunz and Eduardo Eizirik sequenced and compared complete genomes from 38 cats of the genus Leopardus. Twenty six of them belonged to the tiger cat group, and eight genomes came from museum specimens, which let the team test old type specimens, including tiger cats from the Guiana Shield, where the species was first described. The genomes split the tiger cats into five distinct species. One of them, from the Bolivian Yungas, had never been described, and the team named it Leopardus tilcayo. The tiger cats of the Peruvian Yungas turned out to be a separate subspecies, now called Leopardus tigrinus antisuyo.
The paper describes the tilcayo as a small cat with a head and body 42.5 to 50.5 centimeters long, a tail of 25 to 26.5 centimeters, a light brown back that gets darker along the spine, and large, irregular, mostly open dark rosettes that do not merge. In its genome, about 1.4 million sites out of more than 29 million variable ones set it apart from its closest relatives. The researchers say it is the first new living cat species described in more than a century.
The name was not invented in a lab. People in the Bolivian Yungas already called this cat tilcayo, and the authors kept that word as both the scientific name and the English common name. How many tilcayos live in the wild is still unknown, and the authors write that the clearer list of species is what conservation planning for these threatened cats needs.
