- Sri Lanka is home to 10 known species of blindsnakes, a family of soil-burrowing snakes so small that they’re often mistaken for earthworms.
- The most widespread of these is the flowerpot blindsnake (Indotyphlops braminus), which is also the most widely distributed invasive snake in the world, having accidentally hitched rides as far as North America, Africa and Australia in flowerpots for the exotic plant trade.
- A 2020 study, and its 2021 follow-up, proposed moving the species from the genus Indotyphlops to the new genus Virgotyphlops because of its reproductive characteristics that are different from those of other Indotyphlops species.
- But a new study by Sri Lankan researchers, building on field surveys carried out since 2007, says such a move isn’t warranted, and that the flowerpot blindsnake i s simply an “exceptional” member of its genus.
COLOMBO — Look past the venomous vipers and cobras and the powerful constrictors. Dig a little deeper — literally, into the soil — and you might find one of the most unassuming snake families around: the blindsnakes.
The tropical herp haven of Sri Lanka is home to 10 known species of blindsnakes, among them the curiously named flowerpot blindsnake, Indotyphlops braminus. The last known study on blindsnakes in Sri Lanka was carried out in 1947, and a systematic survey has been underway for more than a decade now to provide a much-needed update. As the first in a series of findings aimed at filling this research gap, a newly published study by Sri Lankan herpetologists casts a fresh light on the distribution and genetics of I. braminus.
These snakes are so small, no more than 10 centimeters (4 inches) long, that they’re often mistaken for worms. They live within the soil, leaf litter, or under rocks, boulders or tree trunks, where there’s not much need for good vision. Hence the name, blindsnakes. The scales over their eyes, which in other snakes is transparent, is opaque in blindsnakes, although they’re believed to be able to register changes in light intensity.
The flowerpot blindsnake also has the distinction of being the most widespread invasive snake species in the world. It achieved this through, well, flowerpots: it’s habit of burrowing in the soil, including in home gardens, means countless of these tiny snakes were unknowingly scooped up into flowerpots, many of them destined for export around the world. And this happened over the course of decades.
Their native range is believed to be South Asia, but they’ve now been introduced to 118 countries, from North America to Africa to Australia.
Another characteristic that sets them apart from other Indotyphlops species is the fact that they’re parthenogenetic: all flowerpot blindsnakes and female, and their embryos develop without the need to be fertilized by sperm.
For the Sri Lankan herpetologists behind the new study, a key question to address was whether the flowerpot blindsnake belongs in the genus Indotyphlops, or is the sole species in the genus Virgotyphlops, as proposed in a 2020 study. That study made the case that “[t]he parthenogenetic nature alone of I. braminus warrants recognition of this species as a new genus that is separate from its most closely related snakes of the Indotyphlops pammeces species group.”
Not so, said Nethu Wickramasinghe, lead author of the new study and a doctoral candidate at the University of Colombo’s Institute of Biochemistry, Molecular Biology and Biotechnology. The flowerpot blindsnake just happens to be an “exceptional” Indotyphlops species, she said.
“One of the main setbacks in major blindsnake studies [is] that most often these studies are considered exclusive molecular phylogenetic analyses due to the very cryptic nature of the species,” Wickramasinghe told Mongabay.
She said this reliance on molecular phylogenetics, or gene sequencing to determine a species’ evolutionary family tree, often leaves out the physical characteristics, or morphology, of the species, leading to misinterpretations about its true natural diversity. That makes it very important to carry out integrated taxonomic approaches rather than exclusively concentrating on molecular phylogenetics, Wickramasinghe told Mongabay.
For their study, the research team rooted around in the soil at more than 1,000 locations throughout Sri Lanka since 2007. They found flowerpot blindsnakes at 780 of the sites, establishing that the snake is widespread in Sri Lanka. The vast majority of these sites, 771, were at elevations of less than 1,424 meters (4,672 feet), said study co-author Mendis Wickramasinghe, president of the Herpetological Foundation of Sri Lanka. But they didn’t find blindsnakes in Northern province and adjoining parts of Eastern province. Blindsnakes need moist soil, and these regions are some of the driest habitats on the island, so it’s possible they’re not suitable for the species, according to Mendis, the husband of Nethu Wickramasinghe.
The researchers collected 15 flowerpot blindsnake specimens from different sites for genetic analysis, and found strong genetic similarities between them. In fact, comparing genetic patterns, the researchers found the Sri Lankan species to be similar to flowerpot blindsnakes found in many parts of the world, including India. But in the latter country, there are also certain populations of blindsnakes with different genetic patterns, indicating the possibility these may be a different species altogether. This finding also highlights the need for more research to address the ambiguities, Nethu Wickramasinghe said.
For the researchers, the key takeaway from their study was that the flowerpot blindsnake does indeed belong to the genus Indotyphlops, and not Virgotyphlops as the 2020 study proposed.
“[W]e recommend that I. braminus is currently best recognized as a phenotypically exceptional species of Indotyphlops rather than, as recently proposed, the only species of a monotypic genus (Virgotyphlops),” the study concluded.
More research in the works
Sri Lanka is home to 10 species of blindsnakes, eight of them found nowhere else on Earth. Despite this rich endemicity, there’s been very little research on the blindsnakes of Sri Lanka, with the last proper study conducted in 1947, when five endemic species were described as new to science. It would be another 60 years, in 2007, before another concerted effort to learn more about the island’s blindsnakes, led by Mendis Wickramasinghe and his team.
A veteran herpetologist, Mendis has already described several new-to-science species of reptiles and amphibians and published more than 100 studies. Hs wife, Nethu, has often supported his work as his main research assistant.
“We have several more studies for release on blindsnakes and we will work on it slowly,” Nethu said. “As there is research interest in blindsnakes at a global scale, more research outcomes are expected in the near future. We can also incorporate these findings and create a better output.”
Wickramasinghe, N., Wickramasinghe, L. J., Vidanapathirana, D. R., Tennakoon, K. H., Samarakoon, S. R., & Gower, D. J., (2022). A molecular-genetics perspective on the systematics of the parthenogenetic flowerpot blindsnake Indotyphlops braminus (Daudin, 1803) (Squamata: Serpentes: Typhlopidae). Systematics and Biodiversity, 20(1), 1-16. doi:10.1080/14772000.2022.2062478
Wallach, V. (2020). How to easily identify the flowerpot blindsnake, Indotyphlops braminus (Daudin, 1803), with proposal of a new genus (Serpentes: Typhlopidae). Podarcis, 11(1), 4-12. Retrieved from http://www.podarcis.nl/Podarcis/VolumesNewSeriesUK/PodarcisUK_42.pdf#page=4
Wallach, V. (2021). Addendum to the proposal for a new generic name, Virgotyphlops, for the species Eryx braminus Daudin, 1803 (Serpentes: Typhlopidae). Podarcis, 12(1). Retrieved from http://www.podarcis.nl/Podarcis/ArticlesNewSeriesUK/PodarcisUK_166.pdf
Banner image of a blindsnake, easily distinguished by the opaque scales covering the eyes, reducing the eyes to small dark spots, courtesy of Bushana Kalhara.