Guwahati: In a landmark discovery that reshapes the understanding of reptilian evolution in South Asia, a team of Indian and international researchers has identified a new species of day gecko in Assam. Named Cnemaspis brahmaputra, the diminutive reptile was discovered near the Dirgheswari Temple in North Guwahati and has been confirmed as a member of the podihuna clade — a lineage previously believed to be almost exclusive to Sri Lanka.
The discovery, published in the latest issue of the journal Taprobanica, marks only the second time a species from this ancient clade has been reported from mainland India. The new species is genetically and morphologically distinct from its Indian sister species, Cnemaspis assamensis, as well as from all known Sri Lankan congeners.
The species was described by Amit Sayyed, Madhurima Das, A.A. Thasun Amarasinghe, Rupankar Bhattacharjee, and Jayaditya Purkayastha in Taprobanica: The Journal of Asian Biodiversity (Vol. 14, No. 2, 2025).
“This gecko is not just a new species — it’s a living fossil that tells the story of how species may have dispersed between South Asia and Sri Lanka during ancient geological periods,” said Dr. Amit Sayyed, lead author of the study and a member of the Wildlife Protection & Research Society, Maharashtra.
The podihuna clade to which Cnemaspis brahmaputra belongs has long been considered endemic to Sri Lanka. Its sudden appearance in Assam — over 1,400 km away — is being seen as evidence of prehistoric faunal exchange between Northeast India and Sri Lanka, likely facilitated by rainforest corridors during the Paleogene period. The researchers suggest this could also explain the presence of several morphologically cryptic species in the region.
Genetic analyses revealed that C. brahmaputra differs from C. assamensis by 6.0–7.2% in the mitochondrial ND2 gene, and by more than 18% from its Sri Lankan relatives. This level of divergence confirms its status as a distinct species. The Brahmaputra River appears to act as a natural barrier between the two Indian species.
“This discovery highlights how underexplored and biodiverse Northeast India is,” said co-author Dr. Jayaditya Purkayastha from Help Earth, Guwahati. “More such relict species may be waiting to be discovered.”
Cnemaspis brahmaputra is a small, rock-dwelling, diurnal gecko measuring around 31–35 mm in snout-to-vent length. It features a pattern of dark brown and pale yellow markings, a moderately elongated head, and distinctive scale counts that set it apart from its relatives.
Notably, it has no enlarged tubercles on its lower flanks, and males bear 6–7 precloacal pores and 12 femoral pores — more than any other species in the podihuna clade. These features, along with its tail morphology and head shape, were confirmed through detailed morphometric and statistical analyses, including Principal Component Analysis (PCA).
The researchers named the species after the Brahmaputra River, one of Asia’s largest and most ecologically significant rivers, which flows close to the type locality.
The gecko was found in a moist deciduous forest habitat interspersed with granite outcrops and boulders — conditions that the authors suggest act as climate refugia, or long-term shelters for biodiversity. However, urban expansion around Guwahati threatens such habitats.
“Species like C. brahmaputra are particularly vulnerable to habitat loss due to their limited range and ecological specialization,” said Dr. Madhurima Das of Assam Don Bosco University, another co-author.
The study adds urgency to conservation efforts in Assam and calls for more surveys in surrounding hill forests and riverbank ecosystems.
With this discovery, scientists now believe that the northeastern hills of India — much like the Western Ghats — could be hiding a treasure trove of ancient reptilian lineages. The authors suggest that several more undescribed species within the Cnemaspis genus likely exist in this biogeographically complex region.
“This is just the beginning,” said Dr. Sayyed. “We need to look closer at the granite rocks and forested hills of Northeast India — they may well be cradles of evolution.”
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