New species of 'dragon millipede' discovered in a cave

Scientists documented a spiny dragon millipede mating on a cave wall in northern Thailand and confirmed it as a new species. The team reports at least a 10 percent DNA gap from close relatives. 

The discovery comes from a 2024 biodiversity survey at Pha Daeng Cave in Mae Hong Son Province. The animal hugs humid rock surfaces and moves in tight crevices where moss keeps the stone damp.

New member of Desmoxytes

The work was led by Ruttapon Srisonchai, a biologist at Khon Kaen University and Chulalongkorn University. His research focuses on millipede systematics and Southeast Asian biodiversity.

This species belongs to Desmoxytes, a group known for sharp lateral spines and ornate body shapes documented in a comprehensive revision. Those spines do not form wings, but they jut from each ring and create a jagged silhouette.

Its body is dark brown, which helps it blend against wet limestone. Long, slender legs and antennae let it probe fissures where water seeps.

The population so far is confined to the cave and a few nearby sites in Mae Hong Son. That narrow footprint marks it as a specialist that depends on a stable rock wall microclimate.

How scientists labeled it Desmoxytes

Researchers used integrative taxonomy, a method that combines visible traits with DNA evidence to test species boundaries, to make the call. They examined shape details, then added gene sequencing to check whether the lineage stands apart.

Using an integrative approach that combined morphological and molecular data, the researchers compared three gene regions and built a phylogeny, a family tree that maps how species are related.

One gene, COI, is the workhorse for animal identification because a short segment often separates species cleanly.

That approach to genetic identification, known as DNA barcode analysis, helps flag hidden diversity in lookalike animals.

In their dataset, the new millipede’s COI sequence differed by roughly 11 to 19 percent from its nearest Desmoxytes neighbors. That gap is large for animals that live side by side on the same rocks.

The decisive traits were not just DNA. The authors also studied the male gonopod, the reproductive leg used to transfer sperm, which often carries species level shape signals in millipedes.

Life on limestone walls

The species lives on limestone in a karst landscape, rock that dissolves in water and forms caves, sinkholes, and springs. This terrain creates a maze of moist surfaces, tiny ledges, and shaded pockets.

The animals were seen moving along damp rock while moss held moisture on the surface. Based on current data, the species appear to be narrow endemics that thrive only on limestone rock wall habitats, relying on the constant humidity and shaded conditions of these caves.

Biologists use the term endemic, found in one place and nowhere else, when a species has such a tight range. Cave wall specialists like this one can vanish if their few sites are damaged.

Thailand sits within a belt where limestone quarrying and development pressure meet rich cave biodiversity.

A few researches identified karst systems across Southeast Asia as home to unusually high endemism and as hotspots facing quarrying risk.

What the body shows

Dragon millipedes carry raised plates on each ring, and many species show dramatic spines that protrude from the sides. That armor gives the body a toothed outline that looks like a row of small fins.

The new species, named Desmoxytes chaofa, shows a dark brown color with jagged projections that echo the group’s trademark look. Its long legs and slim antennae fit life on slick rock where steady contact matters more than speed.

Color and body proportions help separate it from close relatives, but the fine points are in the reproductive anatomy. Those features, once sketched and compared, lined up with the DNA tree to support the species status.

The authors also describe a second species in the same paper, one with pink legs from another Thai province. That find underscores how much diversity remains tucked into narrow rock habitats.

Lessons from this Desmoxytes millipede

Every cave wall specialist adds a piece to the map of life, especially in places where few surveys reach steep or dim rock faces. These animals hold clues about how isolation and moisture carve evolutionary paths over short distances.

Documenting them also sets baselines for future checks. If quarrying, tourism, or drought touch these few sites, scientists will know what is at risk and where to watch first.

This case shows how field notes, careful drawings, and gene sequences work best together. The DNA gap lights the path, and the anatomical match confirms the step.

The study is published in Tropical Natural History.

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