The family tree of hedgehogs ends in 2023, receiving several more branches. A study published on December 21 in Zoological Journal of the Linnean Society identified five new species of soft-furred hedgehogs native to Southeast Asia that were discovered using some DNA analysis and some museum specimens from decades ago.
[Related: Why Danish citizen scientists were on a quest to find the oldest European hedgehog.]
Fur instead of spines
Soft-furred hedgehogs – or gymnures – are small mammals that are members of the hedgehog family. Instead of being covered in spines like other hedgehogs, they have soft fur. Hedgehogs are not rodents and have a pointed snout like their relatives. Scientists previously thought there were only two species, but this new study increased that number to seven.
These newly discovered species belong to a group of soft-furred hedgehogs called Hylomys that live in Southeast Asia. Two of the hedgehogs are an entirely new species of soft-furred hedgehog. They are named Hylomys vorax and Hylomys macarong both are endemic to an endangered and incredibly biodiverse rainforest in North Sumatra and South Vietnam called the Leuser Ecosystem.
H. macaron it has dark brown fur and is about 5.5 inches long. It is named after the Vietnamese word for vampire – Ma cà rồng – because the males have fang-like incisors. Further field studies are needed to understand what these teeth do, but their larger size suggests they may play a role in sexual selection. Males also have rust-colored chest markings that may have been colored by scent glands.
H. insatiable is slightly smaller at 4.7 inches long and also has dark fur. It has a black tail and a very narrow muzzle. It is thought to occur only on the slopes of Mount Loiser in North Sumatra. It is named after a description made by the mammalogist Frederick Ulmer, who collected the specimens during an expedition to Sumatra in 1939. Ulmer identified it as a species of earthworm in his field notes.
“They were voracious beasts, often devouring the entire bait before releasing the trap,” Ulmer wrote. “They ate ham rind, coconut, meat and walnuts. A groundfish partially swallowed chicken head bait on a steel trap before being caught in a nearby Schuyler trap baited with ham rind.’
The other three were promoted from subspecies to species. A subspecies is a smaller group within a species. They are genetically distinct from other groups within the same species, but can still interbreed and produce viable offspring. These three were originally considered a subspecies of Hylomys suillus, but the study found enough genetic and physical differences to be upgraded to species. They are named Hylomys dorsalis, Hylomys peguensis and Hylomys maxi.
H. dorsalis lives in the mountains of North Borneo and has a dark stripe on its head that bisects its back.
H. peguensis is only 5.1 inches long with more yellow fur and can be found in many countries in mainland Southeast Asia.
True to its name, H. maxi is also at the larger end of the new species of soft-furred hedgehog at 5.5 inches and can be found in the highlands of the Malay Peninsula and in Sumatra.
According to study co-author and evolutionary biologist Arlo Hinckley, soft-furred hedgehogs generally look more like a cross between a mouse and a mouse because they lack the spines of their cousins. These small mammals are usually active both during the day and at night and are omnivorous. They probably eat a wide variety of insects and other invertebrates, as well as fruit, if available.
“Based on the lifestyle of their close relatives and field observations, these hedgehogs likely nest in hollows and hide while foraging among tree roots, fallen logs, stones, grassy areas, undergrowth and leaf litter,” Hinckley said in statement. “But because they are so poorly studied, we are limited to speculating about the details of their natural history.”
Hinckley is a postdoctoral fellow at the National Museum of Natural History in Washington and at the University of Seville in Spain.
Rummaging through museum drawers
During his PhD in 2016, Hinckley became interested in hedgehogs with soft fur. After studying them in Borneo with study co-author Miguel Camacho Sánchez, their early genetic data and studies of many known populations in Southeast Asia suggest there may be more species than scientists currently recognize. They began searching natural history collections for specimens assigned to this group. Many hedgehogs with soft fur were only skins and skulls preserved.
[Related: Why preserving museum specimens is so vital for science.]
“We were only able to identify these new hedgehogs thanks to the museum staff who have curated these specimens for countless decades and their original field collectors,” Hinckley said.
The H. insatiable the specimen was in the Smithsonian’s collection and sat in a drawer for 84 years. H. macaron spent the last 62 years at the Academy of Natural Sciences at Drexel University in Philadelphia. Hinckley and study co-authors from institutions in the United States, Switzerland, Singapore, Spain and Malaysia ultimately collected 232 physical samples and 85 tissue samples from the entire Hylomys group. They made detailed physical observations and collected measurements to determine differences in the size and shape of their skulls, teeth and fur.
They then began the genetic analysis at the Doñana Biological Station’s Ancient DNA Laboratory in Spain and the Smithsonian’s Analytical Biology Laboratories. The results identify seven distinct genetic lineages and indicate that the number of recognized species in the group is about to increase.
[Related: A key to lizard evolution was buried in a museum cupboard for 70 years.]
“It might be surprising for people to hear that there are still undiscovered mammals,” Hawkins said. “But there’s a lot we don’t know – especially the smaller nocturnal animals, which can be hard to distinguish from one another.”
The team hopes that the description of these new species can expand scientific understanding and be used to protect threatened habitats such as the Leuser ecosystem in North Sumatra. This region faces threats from logging, mining, deforestation from road projects and climate change.
“This kind of research can help governments and organizations make hard choices about where to prioritize conservation funding to maximize biodiversity,” Hinckley said.