According to a new DNA analysis conducted by Brazilian researchers, a rare species of wild cat called the oncilla (Leopardus tigrinus) – one of the smallest wild cats in the Americas – is actually two separate species.

Oncillas, also known as tigrinas, little spotted cats, little tiger cats, tigrillos, or tiger cats, are wild, housecat-sized leopards native to montane and tropical rainforests of Costa Rica, Brazil and Argentina.

These wild cats weight as little as 1.5 kg, and usually do not exceed 3 kg with males slightly larger than females. Their body length can be anywhere between 35 to 60 cm, with a height of about 25 cm. They have a yellowish-ochre background pelage predominantly patterned with open rosettes.

Oncillas eat small mammals, lizards, birds, eggs, invertebrates, and occasionally tree frogs. These cats generally live for 10 to 14 years in the wild, and although they have been known to live for up to 23 years in captivity. They are threatened by habitat loss for cattle ranching, agriculture and local trade for pets.

Zoologists had thought that there was a single species of oncilla, Leopardus tigrinus. However, a new DNA study shows that oncilla populations in northeastern versus southern Brazil are completely separate, with no evidence of interbreeding between them.

To find this, Brazilian scientists led by Dr Eduardo Eizirik from the Pontifıcia Universidade Catolica do Rio Grande do Sul and the Instituto Pro-Carnivoros collected DNA samples from Geoffroy’s cats (Leopardus geoffroyi), pampas cats (Leopardus colocolo), and two separate oncilla populations in Brazil.

They revealed a complicated set of relationships between the oncillas and two other species. That evolutionary history includes ancient hybridization and movement of genes between the pampas cat and the northeastern oncillas.

In contrast, southern oncillas – newly recognized as Leopardus guttulus – continue to hybridize with Geoffroy’s cats, leading to extreme levels of interbreeding between the species along their contact zone. Those patterns add to evidence that hybridization can and does occur between distinct animal species.

As for the two oncilla species – Leopardus tigrinus and Leopardus guttulus, the zoologists suggest that they may be suited to different habitats, with the northeastern oncillas living primarily in savannahs, as well as dry shrub lands and forests, and Leopardus guttulus living in denser and wetter Atlantic forests.

“Such distinct habitat associations provide a hint to potentially adaptive differences between these newly recognized species and may have been involved in their initial evolutionary divergence,” said Dr Tatiane Trigo of the Pontifıcia Universidade Catolica do Rio Grande do Sul, who is the first author of the paper published in the journal Current Biology.

“All four species are threatened, and we need to understand as much as possible regarding their genetics, ecology, and evolution to be able to design adequate conservation strategies on their behalf,” Dr Eizirik concluded.

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Bibliographic information: Trigo TC et al. 2013. Molecular Data Reveal Complex Hybridization and a Cryptic Species of Neotropical Wild Cat. Current Biology 23, 1–6; doi: 10.1016/j.cub.2013.10.046