Protobothrops kelomohy – Omkoi Lance-headed Pit Viper

Protobothrops kelomohy
Protobothrops kelomohy, Omkoi Lance-headed Pit Viper from Tak province, Thailand

The Protobothrops kelomohy SUMONTHA, VASARUCHAPONG, CHOMNGAM, SUNTRARACHUN, PAWANGKHANANT, SOMPAN, SMITS, KUNYA, CHANHOME, 2020, known in English as the Omkoi Lance-headed Pit Viper is a species found in a remote corner of northwest Thailand.
In 2004, my friend Sjon Hauser found a brown colored viper dead on a road in Tak province. After close inspection, he found that the most similar looking species seemed to be the Protobothrops mucrosquamatus, however, there were some minor differences which led him to believe it could possibly be an undescribed species. In the years that followed, Sjon had visited the area multiple times, but never found another specimen.
It was many years later that I got to know Sjon. Both sharing a passion for Thailand’s snakes we decided to meet up and at some point Sjon told me about his discovery of this DOR (dead on road) pit viper he had encountered.

In July 2016, we planned on visiting this region on our first mission to try and find a live specimen of this mystery viper. We invited my other good friend and herp enthusiast, Parinya Pawangkhanant to join us on this expedition.
Surprisingly, after I told Parinya that we were going to look for an unknown Protobothrops species, he mentioned he knew about its presence. But how? Turned out he had found an image in a trip report on a forum online of a live specimen coiled up in a library of a remote school for the hill tribe kids in Omkoi district, Chiang Mai. An image by a local volunteer at the school.

So, with these two records we had a rough range where we should go search for it, but we had virtually no knowledge about this species’ preferred habitat. Well, it seemed to like school libraries… but we dropped the idea of searching every school library in the region 😉 . Would it prefer streams, rocks, forest? Would it spent most of its time on the forest floor, or up in trees? Scanning the internet for in situ photos of other Protobothrops species, we tried to form an image of the most likely habitat. Despite their long size, most Protobothrops species seem to spend more time on the ground than up in trees. But rocky habitats seem to be preferred by many species in this genus. The long slender body shape with keeled scales probably aids in climbing rocky surfaces.

We spent a couple days in the region, the first two snakes of the trip were two Bungarus species following up on each other. First a stunning yellow and black Banded Krait, Bungarus fasciatus, and later a very unusual looking white-banded krait species which to this day is somewhat uncertain what it is. With the very high count of 50 thin white bands, it looked very much like the Bungarus multicinctus, a species so far not recorded from Thailand. However in recent years, it has become more likely that it might just be an unusual variation of the widespread Malayan Krait, Bungarus candidus. Nonetheless, it was a very exciting find at the time.
Despite the long nights, we didn’t succeed to find the mystery pit viper on this expedition.

Then in 2017, a team of the Queen Saovabha Memorial Institute (QSMI) also known as the Thai Red Cross, the snake farm where most of Thailand’s antivenom is produced, organised an expedition to Omkoi in response to a bite case by this unknown pit viper species. With help of the people of the local hill tribes, they eventually managed to retrieve a couple specimens of the undescribed lance-headed pit viper. And that’s where the process of examination and describing of the new species started.

In September 2018, on a long trip through Northern Thailand, I revisited the area to give it another try. This time traveling with my family. At night I would go out alone, drive the one and half hour from the nearest hotel to the region where I expected to have the best chance of finding it. The region’s mountains are largely stripped of their natural vegetation, finding good spots to explore on foot was a challenge.
But I didn’t give up easily. Tried to follow my instinct, even if at times I started to doubt if I would be in the right area. One night I got a bit of an adrenaline rush when I spotted a snake in the bushes that looked quite like a Protobothrops from a distance. But within seconds when I got closer it turned out to be a Many-spotted Cat Snake (Boiga multomaculata). After another night of unsuccessful searching I was driving the long way back to the hotel. It was after 2am, and the road is quiet in daytime, but even more so at night. However, this time I met one vehicle. It wasn’t much further where I suddenly noticed a snake on the road. I jumped out of the car, ran back to the snake and there it was, the Protobothrops species I had spent so many hours trying to find. It should have been a very exciting moment, but the excitement was dampened when I noticed the snake was hit by a vehicle. That one and only car I met must have ran over the snake.
The big female viper was badly injured at midbody, organs and ovarian follicles hanging out of her body 🙁
She was still alive but there was no way she would survive those injuries. Not the way I had hoped my first encounter with this species to be.

The only positive thing to take away from this find was that I now had an exact location where it occurs and that helped somewhat to learn more about their preferred habitat, even though it was still somewhat guessing as finding a snake on a road doesn’t tell much about the preferred micro habitat.

Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) adult female
Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) adult female in Tak province, Thailand

A month later I decided to go there for another trip, and focus all my time around that same location. The first night I found another Bungarus multicinctus/ candidus-variation.
But then the second night I managed to get in a small patch of forest and happened to stumble upon a small limestone rocky spot, it was the kind of micro habitat I had hoped to find. A beautiful bent-toed gecko (Cyrtodactylus sp.) appeared in the corner of my eye, and as I tried to approach it for a closer look, I suddenly noticed an unusual pattern on the rocks. And wow, there it was, my first healthy living specimen of the undescribed Protobothrops species.
After all the efforts put into it, it was quite a joy to finally find it. My cheering in the darkness must have been audible from quite some distance, haha.

Being in the know that the team of the QSMI was working on this undescribed viper, I got in touch with them about my finds, which was interesting since it was not from the same locality where the type specimens were collected.
They invited me to become a co-author, and in the following months, the manuscript was finalized, submitted, reviewed and finally published on 10 March 2020 in the open access Tropical Natural History journal.

A major highlight in my herping career. As a little boy, seeing the sporadic TV news item about a new animal species being discovered always sounded like an exotic idea, a dream for me, yet at the same time something I never expected to be part of myself. But in the last decade when living in Thailand I learned there is actually still lots to discover even in a touristic country like Thailand. New species being described all the time, it’s just that most of those discoveries never make the news for non-naturalists to find out about it. And before I delved deeper into the world of herpetology, I didn’t know better. Nevertheless, being part of describing/ discovering (well, more or less) an all new species of snake is not all that common. And viperids always have been my favorite family of snakes, so that makes it even cooler 😉

The article describing the species can be found at:

Enough about the background story, time for some other info to share about this species. For as far as available…


Dangerous?Dangerous, to my knowledge only one bite has been reported, no fatalities are known at this stage, but with proper health care not too likely I presume; front-fanged, long, foldable, hollow fangs, potent venom; these snakes rely on their camouflage so are not likely to flee. Which means, in the unfortunate case you don’t see it, but unknowingly step on it/ grab it, it may decide to bite.
Lengthup to 131cm possibly longer
How easy to findOnly known from a small area in northwest Thailand. It has taken us quite some effort to find it, however perhaps over time when we learn more about the species, it might be easier; then again, locals hill tribes claim it is less often encountered as in the past.
Best time of yearSo far, most records have been in the wet season.
Best time of dayIt’s hard to say for sure, at least the fatally injured specimen must have been active at 2 – 3AM. We expect them to be primarily nocturnal.
ThreatsLocal hill tribes claim the species is in decline. Our assumption is that habitat fragmentation/ decline is a potential cause. And it seems locals persecute them.
Notes:The team of the QSMI found out this species has some of the longest fangs of any venomous snake species in Thailand. One captive female laid a clutch of eggs in December, though the eggs were infertile. The scientific name is based on the local name in Karen language;
The article describing the species can be found at:


Head top view of Protobothrops kelomohy
Head top view of the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile

The Protobothrops kelomohy is a relatively slender but long pit viper with a large triangular-shaped head. The body tends to have a red-brown/ almost pinkish tinted base color with dark brown markings outlined with a very thin cream/ yellow line. The pattern on the tail seems to form bands. The head has contrasty markings on the upper lip under the eye and on the nose. The ventrals are lighter colored with a vague, somewhat checkered appearance. Scale counts are as follows.
231 – 240 ventrals, 77 – 84 paired subcaudals, dorsal scale formula 23-23-17.

Ventrals of Protobothrops kelomohy
Ventral surface of the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile in Tak province, Thailand

Similar-looking species

Close up adult female Protobothrops kelomohy
Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) adult female in Tak province, Thailand

With a bit of a good look, the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) is fairly easy to distinguish from other snake species in Thailand.
The Brown-spotted Lance-headed Pit Viper or Habu (Protobothrops mucrosquamatus) is the only other Protobothrops species in the country, though so far it has only been recorded in Nan province which is quite a different range from the Protobothrops kelomohy. Another species somewhat similar in body shape and looks, but harmless to humans is the Many-spotted Cat Snake (Boiga multomaculata). Besides these, Thailand has a couple terrestrial viper species in various brown tints like the Siamese Russell’s Viper (Daboia siamensis), Malayan Pit Viper (Calloselasma rhodostoma) and the Himalayan Mountain Pit Viper (Ovophis monticola). But these last three species are much stockier built, so body proportions look very different to the long and slender appearance of the Omkoi Lance-headed Pit Viper.

Head close-up of the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile
Head close-up of the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile
  • Protobothrops mucrosquamatus – Brown-spotted Lance-headed Pit Viper
    This species, also known as Habu, has so far only been recorded in Nan province, so to our knowledge not overlapping with the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy). Probably the easiest way to tell these species apart is the head pattern of these two. The Protobothrops kelomohy has dark markings on the upper lips under the eye and toward the nose. The P. mucrosquamatus lacks such markings. Perhaps less reliable, but still fairly consistently different is the overal color difference, the Protobothrops mucrosquamatus tends to have a more tan base color versus the more redish brown tint of the Protobothrops kelomohy. I’d say the P. kelomohy appears slightly more heavily built than the P. mucrosquamatus.
  • Boiga multomaculata – Many-spotted Cat Snake
    This is a harmless species found in the same range (and throughout most of Thailand). This slender arboral species has a somewhat similar built, though generally more slender. The pattern is usually more rounded spots but is variable so could be fairly similar. The head is the main difference. Even though both the Omkoi Lance-headed Pit Viper and the cat snake have rather distinct head (quite a bit wider than the neck), however, the viper’s head is even larger and more triangular, whereas the cat snake has a more rounded head. From side view the viper has the typical angry look, whilst the cat snake appears somewhat less grumpy 😉 Both species have a dark lance-shaped marking on top of the head, though the Protobothrops kelomohy has rougher edges to this lance-shaped marking.
  • Calloselasma rhodostoma – Malayan Pit Viper
    Malayan Pit Viper (Calloselasma rhodostoma)
    Malayan Pit Viper (Calloselasma rhodostoma) in Yan Ta Khao district, Trang, Thailand
    This species is another brown-colored, venomous pit viper. It lacks the dark upperlip markings under the eye and forward to the nose that are found in the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy). The body appears much shorter (and generally doesn’t reach the same length) and stockier than the Protobothrops kelomohy. Body coloration can be quite similar, the Malayan Pit Vipers are quite variable. However, the markings on the back of the Malayan Pit Viper are clear triangles, one point touching the vertebral ridge.


Close up in situ juvenile Protobothrops kelomohy
This species seems to be an ambush hunter as can be seen in this in situ image of an Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile.

There is little that we know about the behavior. Most likely the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) is a nocturnal species and most likely primarily terrestrial. Though, no doubt they can climb trees. The juvenile I encountered was in an ambush position on a rock. Not sure if the species does active hunts in search for prey, my guess is that they primarily rely on ambush hunting.

Range & habitat

In situ juvenile Protobothrops kelomohy
Habitat of the Omkoi Lance-headed Pit Viper (Protobothrops kelomohy). The juvenile can be seen here, in situ.

The Protobothrops kelomohy has so far been recorded in Chiang Mai province (but only Omkoi district), and Tak province (Tha Song Yang district). The expected elevation is around 600 – 1200m. At the lower elevations the habitat seems to change to a more dry deciduous forest type. So far unsure if they occur there. The higher elevations where it has been encountered are covered in more humid evergreen forest. Limestone rock seemed to be present at most locations though not in great abundance. The Omkoi specimens have been found near streams.


The Protobothrops kelomohy was published on 10 March 2020. Phylogenetic study suggests the closest relatives are Protobothrops kaulbacki and Protobothrops himalayanus.

Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile in Tak province, Thailand
Omkoi Lance-headed Pit Viper (Protobothrops kelomohy) juvenile in Tak province, Thailand

How to find this species in Thailand?

I’ll admit, my experience is still somewhat limited, and it has taken quite some effort to find it. But I guess it could become easier now we slowly learn more and more about this species. I expect it is best searched at night. I don’t know if they hide in daytime. It could be visible in daytime and just relying on their camouflage, but I expect it more likely to be on the move at night. The fragmented habitat, and presence of humans throughout its range, make it somewhat challenging to find spots to walk at night. I prefer to search away from people so I do not bother them, nor theotehr way around 😉 , and if possible in natural habitat, but driving the roads through its range could proof successful. Some other Protobothrops species seem to use road drains a lot. So far I haven’t been able to confirm that for this species, but would not be surprised if they do.

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