A disturbing and unknown bark has led to the discovery of a new species of mammal in Africa

A mysterious bark detected at night in the middle of African forests was the key to identifying a new species of mammal in the genus dendrohyrax, also known as “arboreal hyrax,” Yale University reported on Monday.

The recently described species, “Dendrohyrax interfluvialis”, inhabits the dry and humid forests between the two rivers, the Niger and the Volta, in the coastal regions of south-eastern Ghana, southern Togo and Benin, and southern -western Nigeria.

This discovery dates back to an expedition to Nigeria in 2009, where a group of researchers heard a curious nocturnal, bark-like call that came from a small herbivorous mammal that had different characteristics from those of known hyraxes that live in it. other wooded areas. from Africa, they emit a sound more similar to that of a cry.

“Sometimes a listening ear is as important as a keen eye”said Sargis, curator of vertebrate mammalogy and paleontology at the Yale Peabody Museum of Natural History. “My co-authors John Oates and Simon Bearder were in Nigeria in 2009 looking for galagidae, a group of primates, when they noticed that hyrax calls were different on one side of Niger and the other. All the evidence that we will study later, including the distinctive vocalizations, points to a unique species in the forests between the Niger and the Volta ”.

The adult dendrohyrax in trees typically weighs between 2.2 and 3.1 kilograms, and Although they are about the size of a groundhog, they are closely related to elephants and manatees.

They are generally considered nocturnal and arboreal inhabitants, but Their behavior has proven difficult to study, in part because, unlike most nocturnal mammals in Africa, their eyes do not glow at night, making them more difficult to detect, the researchers explained.

To determine that it was indeed a new species, the scientists responsible for the research studied 418 records of hyrax calls from trees collected between 1986 and 2020 at 42 different sites in 12 countries.

From these recordings, Professor Bearder produced sonograms using the samples of the 96 clearest and most complete records, including 34 records from the population between Niger and the Volta, and 62 others from tree hyraxes. of the West, of the Center. and East Africa. Its duration, frequency range and repetition rates were measured, among other characteristics, as a result, almost all of the calls recorded between rivers were “rattlesnakes”, which differed from the high-pitched calls recorded on the west bank of the Volta and the eastern bank of the Niger.

Sargis and Neal Woodman, another of the co-authors, studied the skulls of 69 specimens of adult arboreal hyrax in six museum collections in Europe and North America. They found subtle but clear differences in the shape and size of the skulls of the specimens collected between rivers and those collected elsewhere. The skulls of Dendrohyrax interfluvialis were shorter and wider than those of their counterparts outside the interfluvial zone, according to the study.

They also found differences in the skins, with the new species having a dark brown color and a lighter yellowish brown color on the flanks and tips, while normal hyraxes vary between a much darker brown color, almost black.

Finally, the genetic analyzes ofThe 21 hyrax tissue samples from across the African rainforest revealed that inter-river populations were genetically distinct from other lineages of hyraxes.

According to the researchers, the Niger and Volta rivers are “important biogeographical barriers for a variety of mammals”, as they prevent them from crossing water easily confined to certain species in a defined territory. They explain that, cn the millions of years of climate change, as well as the expansion and contraction of forests, it is not surprising that “new species” have developed.

Scientists warn that all of this “unique” life in the region between these rivers is seriously threatened by human expansion, which leads to increased logging and hunting of native species for food consumption. That is why they are asking for more effort to create new effective nature reserves that protect this endemic life.

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