New species of Protobothrops from western North Thailand

Left: picture in situ of the Protobothrops specimen found in on 26 August 2004, 9.30 AM on “Highway” 105, 23 km south of Mae Ngao, in Tha Song Yang District, Tak Province.
Environment: Hill evergreen/ dry evergreen forest, with some Karen swiddens nearby, elevation about 750m. Right: the 3 pieces of skin, all that remains from the specimen.

New species of pit-viper discovered in Thailand.

The first record of Protobothrops spec. from western North Thailand—a preview with some historical notes

by Sjon Hauser

A (for Thailand) new species of pit-viper has recently been discovered in Omkoi, a mountainous district of Chiang Mai Province, not far from the border with Myanmar. During this year’s rainy season, a well-equipped Thai expedition was sent to a remote Karen village in the mountains of Omkoi in search for this rare snake. The team was led by Nick Chomngam, a well-known producer and presentator of nature documentaries and dr. Montri Sumontha, one of Thailand’s top herpetologists. Local Karen villagers participated in the hunt for the dangerously venomous snake. Only months earlier a villager from the area was bitten by this pit-viper. Some Karens from the area were familiar with the slender, brown snake. A few years earlier such a snake was hidden in the library of a local school and a picture of it was posted on a blog. When this picture was seen by a seasoned amateur herpetologist, he recognized immediately a species from the genus Protobothrops. Though some 20 species of pit-vipers have been recorded from Thailand, none of the more than ten species of Protobothrops, distributed in China, India, Nepal, Myanmar and northern Vietnam and Laos, has ever been found in Thailand. The existence of a possibly new species of Protobothrops in the mountains became a public secret in some circles of professional and amateur herpetologists.

Experts of the Asian pit-vipers are aware that these snakes encompass many cryptic species, that is, that snakes looking almost completely the same, in fact may belong  to two or more different species. For example, the species Protobothrops mucrosquamatus, with a large range in China, Myanmar and North Vietnam is possibly a “complex” composed of a number of different, but very similar looking species. Therefore, it is not unlikely that the Protobothrops in the mountains of Omkoi is different from all known  Protobothrops-species, and thus a new, not yet described species. Given the prestige that one  earns with the description of a new snake species, in particular when it is a pit-viper, it was to be expected that herpetologists might show a keen interest in the unknown Protobothrops from Omkoi.

This was confirmed by the expedition sent recently to the remote Karen village. What’s more, the expedition turned out to be a great success, that resulted in collecting a dead adult and a living juvenile of the wanted species. Both were deposited at the Queen Saovabha Memorial Institute at Bangkok’s Snake Farm. It is speculated that dr Montri together with dr Lawan Chanhome, director of the institute, and with the cooperation of other scientists will conduct a intensive investigation into the two specimens, including dna research and meticulous comparisons with specimens from a number of the thus far described Protobothrops species. It is only following such research that can be determined whether the Omkoi specimens belong to an already known pit-viper species, or in fact to a new species. It is up to these brave experts to decide. The two snakes are definitely in good hands, as the brilliant dr Montri has much experience in describing new reptile species, e.g. in 2011 he was the first author of a publication on a new pit-viper from Phuket, Trimeresurus (Popeia) phuketensis.

I am eagerly awaiting the publication of the Omkoi-Protobothrops, and many of the readers of my irregular posts on snakes, will certainly do as well. However, it’s possible that we have to wait for a few months or even longer before such a publication may appear.

For the time being, I hope to satisfy my readers to disclose a little more about the snake, and in particular, how I myself got involved with this Protobothrops living on Thai soil. As a matter of fact, I am in the possession of the nearly complete skin of a specimen, that almost certainly belongs to the same species. My snake originated from a site in Tak’s Tha Song Yang district, only thirty kilometers from where the recent expedition scored their two specimens.

It was on a morning in August 2004—in my early days as a snake enthusiast—that I came across a slender road-killed snake during a long ride on my motorbike on the bumpy road from Mae Sariang to Mae Sot along the Burmese border. Because of its slender shape and pattern I initially believed that it was a Many-spotted Cat Snake with a somewhat aberrant pattern. I made a few pictures of it and then collected it. When I had arrived in Mae Sot, I had a closer look at it and realized that it was a pit-viper, but it seemed to be too slender for a Ovophis monticola, the only pit-viper with brown blotches known to occur in northern Thailand. Anyhow, I skinned the snake as it started to smell. In those days I found skinning a satisfying way to preserve many of the characters of an interesting or beautiful snake. In the process, I discarded the snake’s tail, which is difficult to skin. A few days later, in Chiang Mai, I apparently cut off a little piece of the skin to make it fit better in the sheets in which it was to be khluep (plastified) to prevent mites and mould to prey on it—not really the most professional way to preserve an animal that might be of interest to herpetology. This all took place in those good old days when I was as happy and free as a solitary amateur asshole snake enthusiast, hunting snakes on a motorbike, can be. Not much later I saw pictures of Indian snakes and I found that my snake closely resembled Protobothrops mucrosquamatus.

The photograph I had made of the road-killed specimen was of poor quality, not sharp and lacking any detail of the pattern, and by skinning the snake, data on various characters of the snake got lost. Yet, what remains from the snake, still reveals many of its characters that can be important to its proper identification. Here they are.

During the examination of the snake, before I skinned it, I made the following notes:

• Total length 64 cm, tail length 12 cm [>> TaL/TL ratio about 18.8%]

• Sex: Female [apparently I had massaged the tail from the center towards the vent, and this had not resulted in everting the hemipenes]

• an entire anal shield [AS undivided]

• color of the eyes [iris]: yellowish-brown

• Tongue black with pink basis

• DSF [dorsal scale formula] 25 : 23 : “16”. At midbody 23 rows of dorsals of which row 1 and 23 are smooth and all the other rows keeled. Posteriorly all (16) rows are keeled.

• The number of ventral shields was 215. Because a little piece of skin, including the anal shield, was cut off from the posterior end, the actual number could be (a little) higher.

If we compare the data revealed from the skin with those listed for 11 species of Protobothrops pit-vipers in a study by Pan et al. (2013)  it can be concluded that:

The high number of  215+ ventral shields excludes most species in the list as conspecific with the skinned snake from Tha Song Yang.

It fits P. mucrosquamatus, P. kaulbacki and P. himalayanus. The latter two, however, have a rather different coloration and pattern. So, only P. mucrosquamatus seems to be left as a candidate species to which the skinned specimen might belong. The number of dorsal rows at midbody (23) is within the range of P. mucrosquamatus (23-27). But the number of rows at the posterior end (16) is not (17-25 rows in P. mucrosquamatus)!  Actually, the true number of rows of dorsal scales one head length from the vent might be 15, because a piece of skin near the vent was cut off. The distribution of the number of scale rows in a snake species is generally rather stable with little variation. It is therefore unlikely that the skinned snake belongs to the species Protobothrops mucrosquamatus. What’s more, the list shows an uncommonly great variation in some characters of Protobothrops mucrosquamatus, which suggests that the latter might be a “complex” of two or more species.

The dorsal scale row distribution of the skinned specimen fits that of P. jerdonii. However, the high number of ventral scales 215+ excludes it from being a P. jerdonii. It therefore seems more likely that the skinned snake does not belong to any of the known Protobothrops-species and is a new, not yet descibed species in its own. (Since I became more or less convinced that it is a species new to science, I began to refer to it as Protobothrops scholaris, a name that refers to the individual that was spotted in the library of a village school, and probably the first living specimen belonging to the species ever captured in a photograph.)

The number of supralabials I can count from the skin are 8 on both sides, but the actual amount could be one or two higher, as it appears that supralabials closest to the rostrum were torn away during skinning. However, much of the head scalation is intact and a detailed examination of it will possibly shed more light on the affinities of the new species.

Since my ‘discovery’, I have explored the area where I had found the pit-viper a dozen of times, but I never came across a Protobothrops-roadkill again—not much surprising as there was very little traffic on that road until recently.

In 2012-14, I was invited by the great German snake taxonomist dr Gernot Vogel to work together on a number of research papers, but later the cooperation was discontinued. One of these papers  was a survey of snake diversity in the province of Tak. I was happy that this gave me the opportunity to present my rare snake skin as the first record for Thailand of a snake superficially resembling Protobothrops mucrosquamatus. When I sent him a first draft of the paper and a scan of the skin of Protobothrops cf mucrosquamatus, Vogel forwarded the latter to dr Patrick David in Paris, an even greater specialist on pit-vipers of the Southeast Asian region. After examining the scans, David was the opinion that the blotches appeared to be a bit too “squarish” for mucrosquamatus and wisely concluded that only finding another specimen could learn us more about the true character of the snake.

The first international expedition into Protobothrops territory (July 2016)
It was in 2016 that I first met Ton Smits, a snake enthusiast from the Netherlands, whose experience with searching for snakes at night in various parts of Thailand is unsurpassed and who has very sharp eye for finding them. I invited him to come to Tha Song Yang  in order to search for the Protobothrops together. In July 2016 we met in Mae Salit. We were four altogether and searched the area between Mae Salit and  Om Khi for three consecutive nights. I was of little use because of my poor eye sight at night, but the others found some twenty snakes, among them a number of interesting specimens. Though the first ‘large international expedition’ into Protobothrops-territory was quite successful, the Protobothrops did not show up during those nights. In 2017, I made another attempt to find the Protobothrops, now alone, by searching the roads for road-kills both in the Tha Song Yang and Omkoi areas during the day, and subsequently spent three nights with a friend in the ‘Omkoi jungle’. But no Protobothrops was found.

We had just returned from that last trip, when ‘reliable sources’ informed me that two specimens of “Protobothrops scholaris” were collected during Montri & Nick’s recent expedition in the Omkoi mountains. I am happy that sooner or later I may read in a taxonomic or herpetological journal about the species I had been searching for. I expect that the study reveals that it is a new species. The coloration and patterning might be closest to P. mucrosquamatus, an in depth analysis of the many characters of the snake, as well as ‘dna matches’ may reveal that the new species actually has its closest affinities to P. jerdonii , as is suggested by the dorsal scale row distribution of  the snake I had found in 2004.