That Cuban rodent species you never knew about? Turns out it’s two species

Hutias are a strange group of rodents living on various islands of the Caribbean. Although big, and sometimes looking a little plump, they’re active climbers and spend a considerable amount of their lives in trees. They look almost like a cross between a squirrel and a beaver, but are only distantly related to either. Instead, these rodents are in the Cavimorpha group that includes many unusual rodents of the Americas, such as capybaras, guinea pigs and spiny rats. The largest of all the hutias is Desmarest’s hutia (Capromys pilorides), found only in Cuba.

A new study now shows, based on museum specimens, that the Cuban species is actually two distinct species: Desmarest’s hutia on the eastern part of Cuba, and the western conga hutia (Capromys geayi) on the western side.

“We used ancient DNA research methods to investigate the evolutionary relationships between historically old specimens of hutias that had been collected from Cuba in the 19th century, and were now in the collections of museums in Europe,” says study co-author Samuel Turvey, a professor at the Zoological Society of London (ZSL) and expert on Caribbean mammals, both alive and extinct. “These included specimens that had originally been named as distinct species by zoologists over a century ago, but had since been largely forgotten.”

DNA evidence showed that these two animals split around 1.75 million years ago, long before humans arrived in what is today the Americas. For millions of years, a large, deep-water channel split Cuba into two distinct parts, likely keeping the two hutia populations apart. Other Cuban species, such as warblers, were also split by this divide.

Turvey says he doesn’t believe the closing of the channel millions of years ago led to any mixing between the eastern and western species.

“There is no reason to suspect that these two species are now interbreeding, and there is no evidence of such secondary gene flow from our genetic data,” he says. “The evolutionary divergence between them is comparable to that shown by other distinct hutia species elsewhere in the Caribbean, and so suggests that they are now reproductively isolated.”

The IUCN Red List currently categorizes Desmarest’s hutia (sometimes known as the congo hutia) as a species of least concern, and Turvey says he believes it’ll stay that way even with the new species split. He also says that the western conga hutia would also likely have a conservations status of least concern.

“Both … species have relatively broad distributions across different parts of Cuba, and there is no specific evidence that either species has undergone a recent population decline,” Turvey says. “However, there is definitely a need for more quantitative field data to understand the current status and local threats for each species, and we should not be complacent about assuming that they are necessarily doing very well under the current severe economic situation in Cuba.”

Hutias are threatened by habitat loss and degradation due to agriculture and mining. Between 2001 and 2023, Cuba lost 402,000 hectares (nearly 1 million acres) of forest, 11% of which was primary forest, according to Global Forest Watch.

Hutias are also imperiled by invasive predators, particularly dogs and cats. Poaching is also a major threat, and Turvey says it may be a rising concern due to Cuba’s economic crisis linked to COVID-19 and the long-running U.S. embargo on the country.

Already, most of the world’s known hutia species are extinct. Many were pushed to extinction shortly after the arrival of Europeans to the Caribbean islands. Incredibly, the blunt-toothed giant hutia (Amblyrhiza inundata), which disappeared long before European arrival and maybe even before humans settled the islands, was the size of a bear.

The Caribbean islands were once home to many other mammal species, including various species of monkeys and sloths, as well as hutias and solenodons — a strange, shrew-like creature that diverged from all other mammals around 73 million years ago. Another group, the shrew-like nesophontes, are completely extinct.

This study could help lead to happier future conservation outcomes for the hutia. The last hutia on the nearby Cayman Islands went extinct shortly after European arrival, but research has found this animal may be very closely related to or a direct member of Desmarest’s hutia.

The paper’s authors write that this “raises the potential for future reintroduction … and restoration of the historically lost Cayman mammal fauna and the wider ecosystem services (e.g., seed dispersal, regulation of vegetation structure) that this species would have provided.”

Citation:

Henriksen, R. A., Woods, R., Barnes, I., Kennerley, R. J., Borroto-Páez, R., Brace, S., & Turvey, S. T. (2024). Genomics of historical Museum collections clarifies species diversity in Cuban hutias (Capromys). Journal of Mammalogy, 105(6), 1365-1377. doi:10.1093/jmammal/gyae090

This article by Jeremy Hance was first published by Mongabay.com on 6 December 2024. Lead Image: A Desmarest’s hutia in Cuba. Image by Gutisoft via Wikimedia Commons (CC BY-SA 4.0).

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