Trimeresurus cf. popeiorum – Pope’s Pit Viper (Western region)
Pit Viper (Trimeresurus cf. popeiorum) male from Kaeng Krachan national park, Thailand
In the recent paper, Troublesome Trimes: Potential cryptic speciation of the Trimeresurus (Popeia) popeiorum complex (Serpentes: Crotalidae) around the Isthmus of Kra (Myanmar and Thailand) by DANIEL G. MULCAHY, JUSTIN L. LEE, ARYEH H. MILLER, & GEORGE R. ZUG, the authors suggest that there is an undescribed species of viper from the Trimeresurus popeiorum complex present in the West of Thailand and the Northern half of the peninsula. Kaeng Krachan national park happens to be our home base since a couple years, and this park lies right in the middle of the region where this new species is occurring. It is one of the more commonly seen snakes in the park especially from 350m asl and higher.
The authors of the paper did not describe the new species, so we will have to wait for someone to pick this up at some point. That means it will be hard for us to go in full detail on the differences between the ‘real’ Pope’s Pit Viper found in Northern Thailand and this new undescribed species from the Northern Tenasserim range. But at least we can share our images of this species and additional information on behavior and how to find it based on our personal experience with this pit viper species.
Some of the info shared might be based on info found on the true Trimeresurus popeiorum (info that might be retrieved from this species as well, before it was known to be a separate species). But based on the similarities in habitat etc chances are the habits/ details of both species are likely very similar.
facts
| Dangerous? | Potentially dangerous; front-fanged, 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 grab it, it may decide to bite. |
| Venom | Based on the true T. popeiorum some sources state neurotoxic, but most pit vipers seem to be haemotoxic and in reports about bites from this species the symptoms suggest it is primarily haemotoxic |
| Length | about 80 – 90cm |
| Diet | Frogs, rodents, lizards & birds |
| How easy to find | Quite easy to find in right conditions and habitat. |
| Best time of year | Wet season is best, but also humid days in the dry season. |
| Best time of day | Nocturnal, but we have found them in daytime as well. Though some seem to hide in daytime and only show up once darkness falls. |
| Threats | No main threats |
| Notes: | DNA research has indicated that this species should be separated from the highly similar looking population in the North of the country. |
Trimeresurus cf. popeiorum, Western locality of the Pope’s Pit Viper complex female from Kaeng Krachan
Description
Both females and males of the Trimeresurus cf. popeiorum have deep red eyes (except in the juveniles) and a deep red mottled tail. The females are bright lime green with a white ventral line. Males are more grass green usually with a red and white ventral line and a red and white streak starting from the eye. But we have seen males that lacked streaks on the head. This species often has banding on its interstitial skin, and we even have seen specimens that had reddish banding on its dorsal scales over the entire body length.
A strongly banded male pit viper, Trimeresurus cf. popeiorum from Kaeng Krachan national park, Thailand. It shows how variable this species can be.
(Click an image to enlarge and open the gallery view)
Trimeresurus cf. popeiorum adult male full body side
Trimeresurus cf. popeiorum adult male full body top
Trimeresurus cf. popeiorum adult male head side view
Trimeresurus cf. popeiorum adult male head top view
Trimeresurus cf. popeiorum adult male eye
Trimeresurus cf. popeiorum adult male midbody side
Trimeresurus cf. popeiorum adult male tail side view
Trimeresurus cf popeiorum adult male ventral view
Similar-looking species
There are various green pit viper species with similar looks, keeping them apart can be tough in certain cases.
- Trimeresurus popeiorum – Pope’s Pit ViperHard to visibly distinguish. Maybe a future publication will provide more details on morphological differences. The new species might have more visible banding on the interstitial skin than found in the true Pope’s Pit Viper.
Pope’s Pit Viper (Trimeresurus popeiorum) male in Doi Luang national park, Thailand
- Trimeresurus gumprechti – Gumprecht’s Pit Viper
Coloration is mostly the same, though females tend to have golden eyes in T. gumprechti. The males have red eyes just like the Trimeresurus popeiorum, but the black interstitial skin is the main key to tell these apart. And Gumprecht’s Pit Viper is found on the eastern side of North Thailand.
To be continued…
Unmarked male Trimeresurus cf. popeiorum from Kaeng Krachan national park, Thailand. Another example of the variation within this species. Looks more like Trimeresurus fucatus.
Behaviour
Nocturnal and primarily arboreal.
To be continued…
West Thailand’s Pope’s Pit Viper (Trimeresurus cf. popeiorum) female in situ on a sloping forest floor in Kaeng Krachan national park, Thailand
Range & habitat
The Trimeresurus cf. popeiorum occurs in the West of Thailand in the Northern Tenasserim range. We have found them from 350m asl up to about 1000m (the highest accessible area in Kaeng Krachan national park). They prefer evergreen forests and riparian forest, usually in quite densely vegetated areas. We have found them in ambush position on the leaf litter on slopes, but in general they seem to prefer to position themselves on twigs/ branches/ bamboo from just off the ground up to 4 – 5m high.
Pope’s Pit Viper (Trimeresurus cf. popeiorum) male in Kaeng Krachan national park, Thailand
Taxonomy
To be continued…
Trimeresurus cf. popeiorum, Western locality Pope’s Pit Viper male from Kaeng Krachan
How to find this species in Thailand?
Like most green pit viper species the best time to look for them is at night, though we have found quite a few in daytime as well. Like most of the vipers they usually sit and wait in one spot for quite some time. This species sometimes has a different hiding spot in daytime and will move out once it is dark, but often enough they will be in the same spot in daytime as they are at night.
Since night access can be complicated, a late afternoon walk in the dark forest using your flashlight might suffice, it will be easier to spot them this way then without a light. Water sources are often a good spot especially in drier times of the year.
