New spiny mouse species discovered in Sri Lanka's Knuckles

Scientists have formally described Mus dumbara, a new species of spiny mouse endemic to Sri Lanka's Dumbara or Knuckles Mountain Range. The discovery followed more than two decades of morphological and genetic analysis after the initial specimens were collected in 2004.

Researchers laid traps along the forest-farmland boundary in Puwakpitiya village. They used burnt coconut as bait after peanut butter failed to attract local mice. On March 11, 2004, a pitfall trap caught a small, distinctive mouse, with a second specimen caught six days later.

Both were females, no larger than a child's palm, with fulvous-gray fur and spiny guard hairs. They had a slender, naked tail longer than the head and body. Externally, they resembled Mayor's mouse (Mus mayori) but differed in tail length and head shape.

An elusive find

Study lead author Suyama Boyagoda said the Dumbara spiny mouse appears elusive. "In 2014 and 2015, I returned to the same locality and setup a number of traps, but despite the investment of 1,900 trap nights employing the same trapping methods, we failed to find a mouse similar to the first specimen," Boyagoda told Mongabay. This extensive effort yielded no fresh specimens.

The species belongs to the subgenus Pyromys. It can be distinguished from its closest Sri Lankan relatives, Mus fernandoni and Mus mayori, by physical characteristics. Its tail is longer than its head-and-body length. Its hind feet have pinkish-white toes.

The skull has a moderately prominent supraorbital ridge. DNA evidence showed more than 11.7% genetic divergence between M. Dumbara and the other two species. Sri Lanka and India's Western Ghats form a recognized biodiversity hotspot. Sri Lanka's wildlife has evolved along a distinct path.

Conservation concerns for small mammals

Co-author Madhava Meegaskumbura, who collected the first specimen, noted mammals have produced comparatively few new discoveries recently. The discovery adds another species to the short list of recently recognized Sri Lankan mammals.

So far, M. Dumbara has been recorded from just one valley in the Knuckles Range. Its true distribution and population size remain uncertain. The species may occur in other unsurveyed forest fragments, survive at very low densities, or may have declined since 2004.

The Knuckles Range is a UNESCO World Heritage Site. However, less conspicuous mammals can be overlooked in conservation planning. Habitats along forest margins remain vulnerable to road construction, land clearance, encroachment, and plantation expansion.

For a species with a limited elevational range, these pressures could be compounded by climate change. Boyagoda added this may reduce suitable habitat. Given the limited information, Meegaskumbura said M. Dumbara should be treated cautiously as a species potentially at risk of extinction.

Research gaps and needs

Sampath Goonatilake, a researcher with IUCN Sri Lanka, said very little research has been carried out on Sri Lanka's small mammals. He identified several important gaps requiring extensive island-wide surveys to understand distributions and habitat associations.

"One of the biggest needs is a comprehensive taxonomic revision, using both classical taxonomy and modern phylogenetic approaches, to clarify the identity, classification and evolutionary relationships of the species we currently recognize," said Goonatilake.

He told Mongabay that studying small mammals is demanding and expensive. Researchers may spend weeks or months in forests to obtain enough samples, creating substantial logistical costs. Few up-to-date identification guides exist, making accurate field identification difficult.

These animals attract less attention than larger, more charismatic mammals. Addressing these gaps will require sustained funding. A comprehensive research program could cost several million rupees. Collaboration among Sri Lankan universities, government agencies, museums, and international institutions, supported by external grants, will be essential.

Sri Lanka is home to 16 species of rats and mice, with six endemic. The new discovery adds another endemic mammal to the list. The species highlights the island's overlooked biodiversity of small mammals.