An international team of researchers has discovered two new species of the murine genus Colomys living in Africa: one in Liberia and Guinea and one in central and southern Democratic Republic of the Congo and Angola.
An artist’s illustration of Colomys lumumbai. Image credit: Velizar Simeonovski, Field Museum.
Colomys, previously thought to be a monotypic genus, occurs across forested regions of equatorial Africa.
Its name roughly translates to ‘stilt mouse’ for its elongated feet that let it wade in shallow streams to hunt for water-dwelling insects like caddisfly larvae.
“These mice are long-footed, kind of like a kangaroo,” said Dr. Julian Kerbis Peterhans, a researcher at the Field Museum.
“They sit up on their haunches, and they wade through shallow streams with their whiskers on the water’s surface detecting movements, like sonar.”
“They have unusually large brains in order to process this sensory information from their whiskers when they hunt.”
“They’re cute, too. When I caught my first one some 30 years ago, it was the most beautiful African mouse I’d ever seen, it had water repellent fur that’s very thick and lush and warm and cozy. They’re incredibly soft, and they have this remarkable snow-white belly.”
Colomys is closely related to the monotypic genus Nilopegamys, which is known only from one specimen collected in Ethiopia in 1927, making it among the rarest mammalian genera in the world — and possibly extinct.
“These two groups of mice have been confused with one another for a century,” Dr. Peterhans said.
“They’ve been so elusive for so long, they’re some of the rarest animals in the world, so it’s exciting to finally figure out their family tree.”
“They’re sort of underappreciated animals. They’re really cool when you start to learn about their ecology,” said Dr. Tom Giarla, a biologist at Siena College.
“These are semi-aquatic mice, so they’re not just your average, everyday rodents.”
In the study, the researchers conducted the first evaluation of Colomys throughout its broad range, drawing from new field work and museum collections. They compared the animals’ physical traits and analyzed their DNA.
The analyses revealed that within the genus, there were two new species: Colomys lumumbai and Colomys wologizi, named after Congolese independence leader Patrice Lumumba and Liberia’s Wologizi Mountains.
The authors also found that one subspecies actually constituted its own separate species, Colomys eisentrauti, and revised the range of another species, Colomys goslingi.
“The new species we named are part of a global effort to understand the biodiversity of African rainforests and highlight the critical areas to be preserved,” said Dr. Terry Demos, a postdoctoral researcher at the Field Museum.
“There are vast areas of the Congo Basin that have barely been explored in the last seventy years, places that are hard to access due to political instability.”
“We’re not even completely sure how these animals are distributed, there are big gaps.”
The team’s paper was published online in the Zoological Journal of the Linnean Society.
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Thomas C. Giarla et al. Integrative taxonomy and phylogeography of Colomys and Nilopegamys (Rodentia: Murinae), semi-aquatic mice of Africa, with descriptions of two new species. Zoological Journal of the Linnean Society, published online October 8, 2020; doi: 10.1093/zoolinnean/zlaa108
