- A newly discovered endemic scorpion from Sri Lanka, Heterometrus yaleensis, has been named after the Indian Ocean island’s most popular wilderness area, Yala National Park.
- This is the sixth new scorpion species described from Sri Lanka by a research team that has carried out two surveys since 2015.
- Scorpions are a largely understudied group of invertebrates, but the present interest in Sri Lanka’s scorpions was sparked by a series of deaths caused by the invasive Indian red scorpion (Hottentotta tamulus) in the island’s north.
- Sri Lankan authorities foiled an attempt in January to smuggle 200 live scorpions out of the country by a Chinese national, highlighting the need for greater efforts to prevent scorpions falling prey to the illegal wildlife trade.
COLOMBO — Getting out of their vehicle in the middle of the night, armed with small digging tools, UV lights and headlamps, the members of the research team looked like a group of treasure hunters. But they were out looking for scorpions, checking on the arachnids as they came out of their hiding spots at night.
It was during one such an expedition in southern Sri Lanka that the team found the treasure they were looking for: a new species of scorpion that they have described in a recent study.
“The instant we saw this particular scorpion in our study area, we recognized it is different from other scorpions found in Sri Lanka,” co-author Sanjeewa Jayarathne, a researcher at the University of Peradeniya, told Mongabay.
They named it Heterometrus yaleensis, or the Yala giant scorpion, after the location from where it was discovered, close to Sri Lanka’s most popular wilderness area: Yala National Park.
Scorpions from the genus Heterometrus, or giant forest scorpions, are some of the largest in the world. Typically, a male H. yaleensis can grow to a length of about 75 millimeters (3 inches), and a female close to 103 mm (4 inches).
The new species can be distinguished from the features on its pedipalps, the two appendages or arms at the front, the researchers say.
The researchers combed the nearby area and managed to identify a few more individuals of the same species.
H.yaleensis was a chance discovery made by the team of Kithsiri Ranawana, from the University of Peradeniya, and František Kovařík, a Czech arachnologist at Charles University and a global authority on the scorpions of Asia and northeastern Africa. When they found individuals from the new species, their second scientific journey had only just begun.
The team’s first scorpion expedition, conducted in 2015, resulted in the discovery of four new species of scorpions: Charmus saradieli, Reddyanus ceylonensis, R. jayarathnei and R. ranawanai. The last two species were named after researchers Jayarathne and Ranawana for their lifetime of work with one of the least-studied groups of invertebrates. C. saradieli was named after Utuwan kande Saradiel, a bandit turned into legendary hero, considered Sri Lanka’s Robin Hood, for looting from the rich to distribute among the poor.
There’s been increasing interest in scorpion research in recent years in Sri Lanka due to a particular species being identified as the cause of several deaths in the island’s northern Jaffna Peninsula.
Medical practitioners were left puzzled by these deaths. In 2012, they sent several specimens, including live scorpions collected from the home of one of the persons killed by scorpion venom, to the medical school at the University of Peradeniya. These specimens then wound up with Ranawana for identification, which marked the beginning of the new wave of research into Sri Lankan scorpions.
The Jaffna scorpion was not a species previously recorded from Sri Lanka, so Ranawana sought assistance from Kovařík, who confirmed it was the highly venomous Indian red scorpion (Hottentotta tamulus). The scorpion was previously found only in India and Pakistan.
In Sri Lanka, it’s considered an invasive species, having been accidentally introduced to Jaffna between 1987 and 1990, when the Indian Peace Keeping Force (IPKF) was stationed in the island’s north as part of the treaty between India and Sri Lanka to contain the Tamil Tiger rebel group.
“In our attempt to study the distribution of the Indian red scorpion, we found significant research gaps. There had been no proper study of Sri Lanka’s scorpions for over a century,” Ranawana told Mongabay.
Records of scorpions from Sri Lanka by early researchers came mostly from their much broader work on Indian or worldwide scorpions, and they were also based on several often-solitary specimens without exact localities, Ranawana said.
Recognizing the need for extensive studies to update the knowledge base of Sri Lankan scorpions, Kovařík and Ranawana decided to collaborate on a series of island-wide surveys. They carried out their first survey in 2015, and the second in 2018, which resulted in the discovery of H. yaleensis.
Their two surveys have already yielded five scorpion species that are new to science, all of them found only in Sri Lanka. (The sixth, Liocheles australasiae, is found throughout Asia, Australia and the western Pacific.)
Half of the new discoveries turned out to be serendipitous findings. L. australasiae, for instance, was first spotted by a tourist near a hotel in southern Sri Lanka and the species was described after his tip was followed with a scientific study. C. saradieli was discovered by researcher Jayarathne from a pile of timber close to his own house. Jayrathne also discovered R. jayarathnei from a rainforest in southern Sri Lanka during a separate study.
All of this has fueled prospects that Sri Lanka is home to many more scorpion species never before described by science, and sparked calls for more research in this field.
“The invertebrates like scorpions become the least studied fauna in this region,” Ranawana said. “There are opportunities for more research in this area.”
New threats to scorpions
There’s also a sense of urgency to describe these unknown scorpions as the threats they face mount. In January this year, authorities arrested a Chinese national for trying to smuggle out 200 live scorpions.
According to Ranawana, the scorpions were likely destined to be farmed for their venom, which would then be sold for medical research worldwide. “It is not easy to extract venom from the scorpions as they only eject a single drop, and this requires the collection of more numbers to draw a considerable amount of venom,” Ranawana said.
He said this case highlights the importance of taking all preventive measures before poaching of scorpions becomes a serious threat to Sri Lanka’s endemic species. He added it was also possible many scorpions were being targeted for the lucrative pet trade.
Kovařík, F., Ranawana, K. B., Jayarathne, V. A., Hoferek, D., & Šťáhlavský, F. (2019). Scorpions of Sri Lanka (Arachnida: Scorpiones). Part III. Heterometrus yaleensis sp. n. (Scorpionidae). Euscorpius, 2019(283), 1-13. doi:10.18590/euscorpius.2019.vol2019.iss283.1
Banner image of a Buthoscorpio sarasinorum, a non-fatal scorpion endemic to Sri Lanka, looking vibrant under UV lights, courtesy of Sanjeewa Jayarathne.