New species get named after places, people, and physical traits. Rarely does one get named after the reaction it provoked. Meet Calamaria incredibilis, a newly described reed snake from southern China whose stubby, blunt-tipped tail so closely mimics its own head that locals have called it the two-headed snake. When researchers finally realized it was an entirely new species, they reached for the Latin word for "unbelievable."
A study published in Zoosystematics and Evolution formally describes the species from just two specimens collected in Guangxi, China. It had been misidentified as a known species called Calamaria pavimentata, in a region where several closely related reed snakes have turned out to be new species in recent years.
New “Two-Headed” Snake Species Found in China
The snake belongs to a group of small, burrowing reed snakes that are notoriously hard to tell apart. Most have slender, cylindrical bodies and spend the majority of their lives underground, which makes them difficult to study and even harder to classify.
Both known specimens are adult males, measuring roughly 8 inches (20 centimeters), with seven dark brown stripes running the length of the body against a reddish-brown background and a yellowish-white belly edged with dark blotches. The tail accounts for only about 8 percent of the snake's total length, making it unusually short and blunt compared to most snakes.
How DNA and CT Scans Revealed a New Species
In China alone, about six Calamaria species have been described or revalidated over the past decade, a sign that the group's diversity has been underestimated. It took a close look at scale counts, tail proportions, coloration, and DNA to show that these two specimens were something else entirely.
The research team also used micro-CT scanning to produce 3D images of the skull, which confirmed that its anatomy did not match anything previously described.
Calamaria incredibilis differs from its nearest relatives by more than 12 percent genetically, a meaningful gap for a group where many species are nearly identical on the outside.
The name incredibilis refers to the unexpectedly high level of hidden diversity within this group, and to the surprise of finding something so genetically distinct living so close to its relatives.
Two Specimens Found Hundreds of Miles Apart
Both specimens turned up on roads during daytime surveys, which is a strange place to find a snake that supposedly spends its life underground. The first was collected in Ningming County, near the Chinese border with Vietnam, at an elevation of around 3,478 feet (1,060 meters). The second appeared more than 311 miles (500 kilometers) to the northeast, in a national nature reserve in Guilin, at 2,493 feet (760 meters).
Two individuals separated by that kind of distance suggest the species is probably more widespread than current records show. The research team thinks it may even cross into northern Vietnam. For now, with almost nothing known about its population or range, it has been listed as Data Deficient on the IUCN Red List, which essentially means there isn't enough information yet to know how at risk it might be.
Why Guangxi May Hold More Hidden Reptile Species
Guangxi is turning out to be an important region for hidden reptile diversity. Sitting at the junction of southern China and northern Indochina, with limestone karst landscapes, varied elevations, and a complex geological past, the region has likely kept animal populations isolated long enough for new species to evolve.
Several closely related reed snakes have been discovered here, and the research team notes that many historical records of Calamaria pavimentata from across southern China almost certainly contain specimens that were never properly identified.
If one “two-headed” reed snake could be mistaken for another species, others may still be waiting in the area.
Read More: Cannibalism in Snakes Is Not Uncommon — but Could be a Behavior That's Tied to Evolution
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Zoosystematics and Evolution: An unexpected discovery of hidden diversity: a new species of the genus Calamaria H. Boie in F. Boie, 1827 (Squamata, Calamariidae) from Guangxi, China
