Unknown lizard species discovered has lemon-colored stripes

Researchers working in western China have identified a small mountain lizard as a brand new species. The lizard lives in Sichuan’s upper Dadu River valley and measures about 2.5 to 2.8 inches (6.4 to 7.1 centimeters) from snout to vent.

The team named the species Diploderma bifluviale, which is a nod to the junction of two rivers where it turned up.

The new lizard occupies semi-arid shrublands high in the valley, between roughly 7,200 and 8,300 feet (2,195 and 2,530 meters).

How Diploderma bifluviale is different

Diploderma bifluviale males have jagged, lemon-colored stripes along the back, a concealed eardrum, and no throat patch.

In addition, the tongue is wheat-colored, and the snout-vent length (the nose-to-opening-before-tail length) is compact.

The fourth toe, when pressed forward, reaches the area near the ear opening. That limb reach, along with short tails and strong body scales, helps separate this species from neighbors.

Lead author Fengjing Liu works at the Chengdu Institute of Biology at the Chinese Academy of Sciences. The survey spanned several years in the upper Dadu River valley.

Confirming the new lizard species

The team compared DNA from Diploderma bifluviale to DNA from close relatives using the ND2 gene. This genetic material is a mitochondrial DNA segment that is used to compare species.

The researchers also measured body traits and ran statistics to separate look-alikes.

“This discovery highlights the understudied biodiversity of the upper Dadu River,” stated Liu. The genetic signal was clear. 

To strengthen the case, the team analyzed body measurements with principal component analysis, a method that groups specimens by shared variation.

Males and females formed clusters that stood apart from two close relatives that occur in nearby valleys.

Where Diploderma bifluviale lives

Scientists have described the Hengduan Mountains as a global biodiversity hotspot. Steep terrain, strong sun, and sharp daily temperature swings encourage isolated habitats.

The Dadu River carves a classic hot, dry valley, and those conditions push reptiles toward local adaptation. Different valleys often host different sister species.

Across East Asia and the northern Indochinese Peninsula, the lizard genus Diploderma bifluviale has multiplied into dozens of species. A recent open access paper notes the group’s range and fast pace of discovery.

The authors state that this new discovery brings the total number of Diploderma species in China to 47.

Diploderma bifluviale is part of the D. flaviceps group, whose members favor dry river valleys at mid to high elevations. The new lizard inhabits semi-arid shrublands, distinguishing it from its close relatives that live in wetter environments.

Naming Diploderma bifluviale

The species name, Diploderma bifluviale, means two rivers, a direct link to the valley’s geography. It honors the confluence of the Chuosijia and Jiaomuzu rivers in the upper Dadu system, where the lizard lives.

Field teams watched lizards bask and hunt among small, leafed shrubs and rock piles from June to August. Activity peaked between about 9:00 am and 6:00 pm on clear days.

The team suggests the English name Upper Dadu Mountain Lizard, while the Chinese name likewise points to the twin river mouth.

Only a handful of individuals were seen during multiple surveys between 2018 and 2024. This suggests a small and patchy population that might be sensitive to disturbance.

In May 2025, the Shuangjiangkou hydropower project began storing water in the same river system. Any changes to flow, banks, or shrub cover could therefore squeeze habitat for this endemic specialist.

Distinguishing a new species

Taxonomists look for unique combinations of traits that no other species shares. These traits are called diagnostic characters.

They also test family trees using DNA and then check whether the new form is monophyletic, meaning it consists of a single branch that includes all of its members. If multiple lines of evidence agree, the case becomes strong.

A clear geographic anchor matters too, often called the type locality, the specific place where the first described specimen was collected. That anchor lets future researchers compare animals from new sites to the original.

Adaptations of the mountain lizard

Short bodies and tails reduce heat loss during cool nights at high elevation, while stocky limbs and rough scales suit life on sunlit slopes that warm quickly after sunrise.

Color patterns likely play more than a decorative role. Jagged dorsolateral stripes can break up the outline against stones and shrubs during quick dashes, for example. This may deceive predators and give essential camouflage.

Lessons from Diploderma bifluviale

Many East Asia lizards use bright throat patches during displays, but this species lacks a gular spot entirely. That difference may signal a distinct communication style among neighbors.

The new mountain lizard’s shrubland niche contrasts with relatives that use damper riverbanks or forest edges. As with many reptiles of the Hengduan Mountains, habitat choice is a key separator.

Scientists do not yet know the full range or population size of Diploderma bifluviale. They also do not know how far it moves between seasons or whether males defend territories.

Key ecological details remain open, including egg survival, and diet beyond broad insect prey. Long-term monitoring will be needed to track trends and guide protection.

The study is published in the journal ZooKeys.

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