New mountain horned dragon identified in Thailand’s Mae Wong National Park

A new species of mountain horned dragon has been identified in high-elevation forest in Thailand’s Mae Wong National Park, with its unusually small crest spines and DNA helping distinguish it from related lizards.

Named Acanthosaura syrax, the species was described through a taxonomic study combining physical measurements, scale counts and mitochondrial DNA analysis, according to a detailed account published by Bioengineer.org. Its recognition brings the number of recognised species in the genus to 23.

The study examined eight adults collected in 2025 in Mae Wong district, Kamphaeng Phet province, in western Thailand. The male holotype — the reference specimen used to describe the species — was collected at 1,340 metres above sea level. All eight specimens were deposited at the Natural History Museum of Thailand’s National Science Museum in Pathum Thani.

Small spines and distinctive markings

The researchers encountered the lizards in an area previously reported to support Acanthosaura lepidogaster, another mountain horned dragon. They did not find that species at the surveyed high-elevation site. Instead, the animals they collected shared a consistent set of distinguishing features.

Most striking were the reduced spines along the neck and back, described as the smallest recorded in the genus. The neck crest has six or seven short triangular spines, while the dorsal crest consists of small, flat, saw-like scales that diminish towards the tail.

The team assessed 51 characteristics, including body and limb dimensions, scale counts, spine lengths and head-scale arrangements. The lizards also have a small, rounded eardrum, a relatively undeveloped throat pouch and short tails compared with their body length.

Females in the sample were larger than males. The largest female measured 101.2 millimetres from snout to vent, excluding the tail, compared with 69.6 millimetres for the largest male. Both sexes had pale markings at the knees and elbows and a black, diamond-shaped collar at the back of the neck.

DNA supports a separate lineage

Analysis of two mitochondrial genes, COI and ND2, placed all eight specimens together in a lineage separate from the other sampled members of the genus. However, the strength of the statistical support differed between the two markers.

The COI analysis met the study’s thresholds for strong support, with a 99% bootstrap value and a Bayesian posterior probability of 1.00. The corresponding ND2 results were lower, at 76% and 0.78.

The identification therefore rests on the combined physical and genetic evidence, rather than equally strong results from both DNA markers. The genetic work examined mitochondrial DNA, not nuclear genes, and did not cover every population that might belong to the species.

A highland habitat with seasonal activity

Field observations placed the lizards mainly in the park’s upper mountain range above 1,300 metres. Researchers did not encounter individuals below 1,000 metres during their surveys, although the species’ full geographical range remains unestablished.

The animals were active from early to mid-day, basking on rocks, fallen logs, shrubs and cement structures before retreating into forest shelters later in the afternoon. Some were observed feeding on earthworms at dawn.

Encounters were most frequent from April to mid-June, spanning the late dry season and the start of the monsoon. Activity declined in wetter, cooler conditions and was particularly low in November and December, when minimum temperatures reached about 10C.

The proposed English common name is “Syrax mountain horned dragon”, after the fictional dragon associated with Queen Rhaenyra Targaryen. For now, knowledge of its distribution rests on observations within Mae Wong National Park; whether it occurs elsewhere remains an open question.