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African rainforests are home to some of the most beautiful and amazing species on Earth, as evidenced by recent research on some rather unusual water-loving rodents.
A study published today in the Zoological Journal of the Linnean Society describes two species of semiaquatic mice. Living in the Congo Basin and western parts of equatorial Africa, these mice earn their living by hunting insects and tadpoles while wading through shallow waters.
The authors of the new study, led by biologist Tom Giarla of Siena College in New York, took a deep dive into an enigmatic genus of mouse known as Colomys, which is translated as “stilt mouse” due to its elongated legs.
Two of Giarla’s collaborators on the project, Terry Demos and Julian Kerbis Peterhans of the Field Museum in Chicago, had been doing fieldwork in Africa for decades, and they told her about a rather strange rodent species they had been catching near streams. and swamps. in central Africa, a rodent known as Colomys goslingi.
“Based on limited previous research, it allegedly had a huge range, with scattered collection records stretching from Liberia to Kenya to southern Angola,” Giarla explained in an email. “Right away, we suspect that this species could comprise several species, because few tropical rodents have such a wide natural range.”
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To handle better Colomys, the scientists analyzed relevant field work, collected physical samples from museum collections, and took DNA samples. The comparative analysis resulted in the identification of four different species belonging to Colomys, two previously known and two unknown to science.
One of the known species, C. eisentrauti, was elevated from a subspecies to a full-fledged species of its own, and its habitat was defined as restricted to northwestern Cameroon. The other known species, C. goslingi, it was found to have a more restricted range than previously thought. The two newly described species were named C. lumumbai Y C. wologizi, in honor of the Congolese independence leader Patrice Lumumba and the Wologizi Mountains of Liberia.
The authors also took this opportunity to study a rare mouse specimen found in Ethiopia in 1927. This creature was previously assigned to an entirely new genus and species. Nilopegamys plumbeus, and it’s probably extinct. The single specimen exhibited characteristics similar to those seen in stilt mice, such as waterproof fur and elongated legs, but scientists had not been able to figure out where it fit within the evolutionary family tree of rodents.
“Thanks to the curators at the Field Museum, where the only specimen is found, we were allowed to take samples from a piece of dried tissue stuck to his skull,” Giarla said. “I managed to extract DNA from that very old piece of dried tissue and sequenced some of its DNA. I had to do all this work in a special lab space to make sure that no other DNA could contaminate it. When I built the evolutionary tree for all of our Colomys Y Nilopegamys samples, it was clear that Nilopegamys was closely related to Colomys. ”
In fact, they are so closely related that the two groups are now considered sister genera.
Colomys They are mice, but you would never mistake them for the ones that hide inside your walls. They are larger than house mice, with thick brown fur, long whiskers, shiny white bellies, and elongated legs that can only be described as kangaroos. They also have unusually large brains, which may have something to do with their semi-aquatic lifestyle.
“The volume of their skulls is huge relative to other African rodents,” Giarla explained. “We think this is to support the mechanosensory system associated with their long whiskers, which they use to hunt aquatic animals like insect larvae and tadpoles. As far as I know, no other rodent hunts like Colomys“They walk through shallow water with their long feet with their whiskers hanging over the surface of the water, waiting to jump on anything that moves,” he said, adding, “They are weirdos.
Stilt mice are They are mainly found in shallow streams, but have also been seen in swampy areas and the shallow edges of deep rivers. They are also nocturnal, spending the night foraging for food in shallow streams in dense forests, a task made possible by their kangaroo legs. Beyond this, they are a mystery.
“I would love to know more about the behavior and ecology of these animals,” said Giarla.
Also, you would like to include Colomys in some larger comparative studies to better understand the evolutionary processes that give rise to new species in tropical Africa. Giarla would also like to find evidence of Nilopegamys, but fear that the animal is really extinct.
Which brings up an interesting point that has to do with conservation.
Giarla said the new study was motivated by her interest in mapping the spread and evolutionary histories of the small mammals that live in the forests of equatorial Africa, such as rodents, opossums and shrews – animals that don’t get much attention.
“The forests of West Africa, the Congo Basin and the East African rift system face great threats from human activities, such as deforestation and mining,” he said. “Some species with small ranges are likely to go extinct soon if more of the forest is not protected.”
