Family: Viperidae (Vipers)
Subfamily: Crotalinae (Pit Vipers)

Picture: J. Bulian

Calloselasma rhodostoma (Malayan Pit Viper)
Thai: (ngu gap pha)

Length: Up to 100 cm

Occurrence: Resident in the whole of Thailand and is often found under dry leaves, stones or old wood.

Behaviour:
Predominantly nocturnal especially when it is drizzling, but also active during the day. It bites, is an aggressive snake and advances very quickly.

Picture: J. Bulian

Cryptelytrops albolabris (White-lipped Pit Viper)
Thai: (ngu khiau hang mei tong loeng)

Length: 75 cm - male, 104 cm - female

Occurrence: Throughout Thailand

Behaviour/habitat:
The White-lipped Pit Viper is a very adaptable snake which can be found in wooden and bushy open areas up to 500 meters. It is often found near human settlements. It prefers to stay near to the water. The snake is nocturnal and in search for food (rodents, frogs, lizards, birds) they also move on the ground at night. The Pit Viper strikes quickly and accidents with humans happen frequently. White-lipped Pit Vipers mate in Thailand in September and October. The females give birth up to 16 offspring, which are born in a membrane which the babies break open just after birth. The juveniles have the same coloration as the adults

Note:
A normal person cannot tell the difference between the green Pit Vipers. The following Pit Vipers, present in Thailand, have a green colour:

• Cryptelytrops (Trimeresurus) albolabris (White-lipped Pit Viper)
• Viridovipera (Trimeresurus) gumprechti (Gumprecht's Pit Viper)
• Parias (Trimeresurus) hageni Hagen's Pit Viper
• Cryptelytrops (Trimeresurus) macrops (Large-eyed Pit Viper)
• Popeia (Trimeresurus) popeiorum popeiorum (Popes Pit Viper)
• Popeia (Trimeresurus) fucatus *in the works from MALHOTRA & THORPE (2004) not yet entered
• MALHOTRA & THORPE follows, entered here under the name Popeia
• Parias (Trimeresurus) sumatranus (Sumatra Pit Viper)
• Viridovipera (Trimeresurus) vogeli (Bird Pit Viper)

There is a serum against all green Pit Vipers available in Thailand.

Picture: J. Bulian

Cryptelytrops kanburiensis (Kanburi Pit Viper)
Thai:

Length:  70 cm

Occurrence: Province of Kanchanaburi

Habitat/behaviour:
This species was described in 1934 by the British herpetologist, Malcolm Smith, using a female specimen from the limestone mountains around Kanchanaburi. Due to its origin in the province of Kanchanaburi, which was formerly called Kanburi, the snake was then given the name kanburiensis.

Almost nothing is known about the living habits of this snake in its natural environment. We do not know whether the snakes inhabit trees as a natural habitat or whether they live on the ground like the Cryptelytrops venustus which live around the limestone mountains and look very similar. The snakes are active at dusk and at night. The mating season for the snakes is in September and October . During this time the snakes are also active during the day, especially the males, and the chance of meeting this snake in these months is very high. The snakes go into hiding in the dry season and re-emerge at the beginning of the rainy season in April. This is also when the females give birth to their young.

Danger:
One bite and has been documented in literature with reference to the venom of this snake. The bite does not result in death but long-term treatment in hospital is necessary.

Warning, danger of confusing with:
Cryptelytrops venustus, Cryptelytrops purpureomacultus

Picture: J. Bulian

Cryptelytrops macrops (Large-eyed Green Pit Viper)
Thai: (ngu kieo hang mi ta to)

Length: up to 72 cm
However these snakes usually only reach a length of around 50 cm.

Occurrence:
Northern and central Thailand. These little poisonous snakes are often found in the area around Bangkok.

Habitat and behaviour:
This is, just like other species of Pit Vipers, a snake which is active at night. When twilight falls, these snakes leave their daytime hideouts in bushes and trees where they sleep curled up in a ball, and go on the hunt in shrubs and on the ground for frogs, lizards, birds and rodents. Cryptelytrops macrops is easily recognisable from other species of Pit Vipers due to its large yellow eyes. Although these animals usually sit on branches and ignore passers-by, they can bite as fast as lightning.

Danger:
Just like other species of Pit Vipers. The poison may be a little stronger than that of Cryptelytrops albolabris. A poisonous bite does not generally lead to major complications.

Picture: J. Bulian

Cryptelytrops purpureomaculatus (Mangrove Pit Viper)
Thai: (ngu pang ka)

Length: 100 cm

Habitat: To be found on covered river banks, in sumps and in hilly areas.

Behaviour:
An easily excitable, aggressive snake, which advances very quickly over a distance.

Warning, danger of confusing with:
Cryptelytrops kanburiensis, Cryptelytrops venustus

Picture: J. Bulian

Cryptelytrops venustus (Brown-spotted Green Pit Viper)
Thai:

Length: Max. 70 cm, but usually smaller

Occurrence: Between Chumphon and Krabi

Behaviour/habitat:
The Coloured Pit Viper prefers life in the woods and on limestone mountains but can also be found on rubber plantations. The snake is mainly nocturnal. The snakes are active during the day only after heavy rainfall. The snake lives almost only on the ground where it hunts frogs and lizards. The snake is very peaceful and only bites if seriously aggravated.

Danger:
Scientific studies on the strength of the poison have not yet been carried out. Reports from bite victims lead us to believe that the poison is not as strong as the White-lipped Pit Viper. Victims have reported pains but no long-lasting effects.

Warning, danger of confusing with:
Cryptelytrops kanburiensis, Cryptelytrops purpureomacultus

Picture: J. Bulian

Parias hageni
Thai: (ngu kiau hang mai)

Length: up to 116 cm

Occurrence: In the provinces of Songkhla, Suratthani and Trang

Habitat/behaviour:
Parias hageni resides in the flatland rainforests. It can usually be found after rainfall at night. The snakes are active in trees and bushes as well as on the ground. Hagen’s bamboo viper is generally calm snake which does not bite as quickly as most of the other Pit Vipers. This species differs from the other green Trimeresuru species due to the relatively clear markings and especially due to the fact that the animals look very slender.

This species lays eggs. The young snakes, hatching from the 13 to 17 eggs after an incubation period of approximately 35 days, are approximately 240 mm long.

Venom:
Although Parias hageni rarely bites, it is recommended that care is taken with this species. There are no recorded deaths caused by a bite from the species that bites can lead to extremely painful swelling.

Picture: J. Bulian

Parias popeiorum (Pope's Pitviper)
Thai: (ngu kieo hang mi tong kieo)

Length: Up to 90 cm

Occurrence: To be found in central and west Thailand in the rain forest.

Behaviour:
A nocturnal, aggressive and biting snake which advances very quickly over a distance. During the day it lies around in the trees. At night it is on the move on the ground.

Picture: J. Bulian

Parias fucatus
Thai: Ngu khiau hang mai

Length:  up to 85 cm however the snakes are usually smaller.

Occurrence: Southern Thailand from Chumphon to the Malaysian border

Habitat/behaviour:
There is hardly any information about the living habits of this species because it was first described in 2004 with an example from Nakhon Si Tammarat. Due to the fact that this species belongs to the Parias popeiorum group and was also recorded as Trimeresurus popeiorum up until 2004, we can assume that it has the same habitat and behaviour as the Parias popeiorum. In addition to the scales and the different DNA, this species differs from Cryptelytrops albolabris and Parias popeiorum with the slightly longer head and the bands across the front of the body. However, it is generally difficult for someone, especially someone who has not intensively studied the species, to differentiate between the different snakes.

Danger:
Tests on the effects of the poison have not been performed yet but we can assume that it is similar to Parias popeiorum.

Picture: J. Bulian

Trimeresurus wiroti (Wirots palmviper)

Length: up to 89 cm, usually smaller

Occurrence: Southern Thailand in the provinces of Krabi, Nakhon Si Thammarat, Narathiwat and Trang

Habitat/Behaviour:
Trimeresurus wiroti inhabits mostly lowland rainforests and tropical wet forests up to 750 meters. According to information’s from local snake catchers in southern Thailand, this species mostly is found near brooks, rivers or ponds. Most animals were found on the ground, near the ground or on bushes. In the recent literature there are also references about sightings in the treetops more than 20 meters above the ground. The snakes are nocturnal and feed mostly frogs. But also birds and rodents are accepted.

At the original place where the snake was found first (the typus was found there) Baan Hui Hip, Amphoe Chawang in the province of Nakhon Si Thammarat this snake probably can not be found any more, as nearly the whole area was transferred into rubber plantations. Also none of the villagers there, which I questioned in 2004, could remember to have seen this snake in the last 10 years. The occurrence in the Thungsong area and south of this is certain.

The snake lays eggs. Between 13 and 17 eggs are deposit, which the female incubates. The hatchlings have a total lengths of about 240 mm at birth.

Besides the here shown red-brown colour variation there are grey-brown animals with black spots on the back or grey to grey-brown specimen with green or greenish spots.

Danger:
Whereas from some authors the venom of Trimeresurus wiroti is described as mildly venomous, one should handle the snake with care. A bite with both fangs from an adult snake, for sure has serious consequences

Picture: J. Bulian

Tropidolaemus wagleri (Wagler's Pitviper)
Thai: (ngu kieo tuk gae)

Length: Max. 100 cm. The male remains smaller than the female.

Occurrence: In southern Thailand from the Khao Sok National Park and Takua Pha up to the Malayan border.

Behaviour/habitat:
The Wagler’s Pit Viper is nocturnal snake and a resident of the lowlands. It lives in primary and secondary forests and in mangrove forests. In these forests, it is mostly found in bushes and on branches at a height of 2 meters. These snakes do not move very much and sometimes spend weeks in the same spot without moving. In general, the animal does not bite quickly but can strike out extremely quickly.