A venomous snake described in 1864 turned out to be five separate species

The Himalayan pit viper, first described in 1864 and treated ever since as one widespread species, is actually five separate species, according to a taxonomic revision published in the open-access journal ZooKeys. Three of the five are entirely new to science: the Hindu Kush pit viper, Gloydius hindukushensis, from northwestern Pakistan; the Hazara pit viper, Gloydius hazarensis, from northeastern Pakistan; and the Nepali pit viper, Gloydius nepalensis, from western and central Nepal. The other two lineages are the original Himalayan pit viper in its strict scientific sense, Gloydius himalayanus, and Gloydius chambensis, a species already described back in 2022.

The international team, led by Daniel Jablonski of Comenius University Bratislava, combined fresh genetic sampling with DNA extracted from museum specimens collected in the 19th and early 20th centuries, including one of the original syntypes of the Himalayan pit viper gathered more than 160 years ago. Jablonski said these mountain systems still harbor overlooked vertebrate diversity and hold important clues to the biogeography of Asia, a region his team has spent years documenting across Pakistan and Afghanistan.

Four Genes and 160-Year-Old DNA Untangled Five Hidden Lineages

Researchers analyzed four mitochondrial and three nuclear genes across populations spanning the western and central Himalaya and the Hindu Kush, many sampled genetically for the first time, and recovered five well-supported, genetically distinct lineages rather than the single species long assumed. Genetic distances between those lineages ranged from 9.2% to 12.6% in the cytochrome b gene and 8.1% to 14.1% in the ND4 gene, divergence wide enough, paired with distinct skeletal and physical traits, to support treating each lineage as its own species rather than a regional variant of one.

To stabilize the group’s scientific naming going forward, the team also designated an official lectotype for the original 1864 description, Halys himalayanus Günther, using a syntype specimen catalogued as BMNH 1946.1.19.64. The single-species assumption had persisted so long largely because the high mountain ranges where these snakes live rank among the least biologically explored regions of Asia, leaving researchers to work from scattered, decades-old sampling rather than a continuous survey of the group.

Beyond DNA and external measurements, the team also ran micro-computed tomography scans on skulls collected across the group’s range, adding osteological data that most snake taxonomy studies skip because of the cost and specimen access it requires. Those scans, combined with the genetic splits, gave the researchers three independent lines of evidence pointing toward the same five-way division, rather than a single genetic marker that critics could dismiss as an artifact of isolated population differences alone.

Three New Species Came From Pakistan and Nepal

The three previously unrecognized species come from different corners of the region: the Hindu Kush pit viper from the eastern foothills of the Hindu Kush in northwestern Pakistan, the Hazara pit viper from the Hazara region of northeastern Pakistan at the western margin of the Himalaya, and the Nepali pit viper from western and central-western Nepal. Jablonski said each of the newly recognized species seems to occupy a relatively restricted range within fragile mountain environments, a pattern that raises new ecological and evolutionary questions rather than closing them.

Museum Specimens From the 1800s Still Held Unread Evidence

Sylvia Hofmann of the Museum Koenig, part of the Leibniz Institute for the Analysis of Biodiversity Change, said museum specimens are not just records of the past — they are active research tools and essential infrastructure for future science. Some of the decisive evidence, she said, had sat unrecognized in museum drawers for more than a hundred years simply because researchers previously lacked the analytical tools to read it, a gap she expects to keep narrowing as genetic methods improve.

Frank Tillack of the Museum für Naturkunde Berlin, who has collaborated with Nepalese researchers on the region’s reptile and amphibian biodiversity for 35 years, said the team’s work aims to close gaps in the group’s known diversity and lay groundwork for further study of snakes he called ecologically and medically important. Pit vipers occupy a role as top predators within their mountain ecosystems, functioning as pest-population controllers and ecological indicators that herpetologists say have historically been studied far too little across the Himalayan range.

Pakistan’s High Mountains Are Still Full of Undocumented Snakes

Rafaqat Masroor of the Pakistan Museum of Natural History, one of the country’s leading herpetologists, said Pakistan’s high mountains are still full of biological surprises, and that the discovery reveals how little is actually known about a region long shaped by political instability. Masroor’s point doubles as the revision’s rationale: the 70-page study, published in ZooKeys volume 1280, set out to narrow that exact gap, drawing on co-authors based in Germany, Slovakia, India, Pakistan and Nepal.

Without recognizing that hidden diversity in the first place, the researchers noted, conservationists cannot accurately assess which of the five species are actually at risk or build an effective plan to protect them. Each of the three newly named species is currently known only from the specific valleys and slopes where it was collected, which means a single road, mine or land-use change in the wrong place could threaten a species before scientists have finished describing it.

The Himalayan pit viper split fits a pattern researchers have now flagged across Asia’s mountain snakes more broadly. A vivid green pit viper hiding in Sichuan’s misty mountains was revealed as its own species earlier in 2026 after DNA testing overturned decades of assumptions that it was simply a common, widespread snake, and a separately overlooked pit viper in Myanmar turned out to blur the usual boundaries between species almost entirely. Taxonomists working across the region say assuming a single species based on a 19th-century description, rather than testing that assumption with modern genetics, is exactly the habit these repeated discoveries are now forcing them to abandon.

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This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.