in a 1916 illustration
Calloselasma is a monotypic genus created for a venomous pitviper species, C. rhodostoma, which is endemic to Southeast Asia from Thailand to northern Malaysia and on the island of Java. No subspecies are currently recognized.
Attains an average total length of 76 cm (30 in), with females being slightly longer than males. Occasionally, they may grow as long as 91 cm (36 in).
A specimen with a total length of 81 cm (32 in) has a tail 9 cm (3.5 in) long.
Dorsally it is reddish, grayish, or pale brown, with two series of large, dark brown, black-edged triangular blotches, which are alternating or opposite. There is also a thin dark brown vertebral stripe, which may be interrupted or indistinct in some specimens. The upper labials are pink or yellowish, and powdered with brown. There is a broad, dark brown, black-edged diagonal stripe from the eye to the corner of the mouth, with a narrower light-colored stripe above it. Ventrally it is yellowish, uniform or powdered or spotted with grayish brown.
The smooth dorsal scales are arranged in 21 rows at midbody. Ventrals 138-157; anal plate entire; subcaudals 34-54 pairs.
Snout pointed and upturned. Rostral as deep as broad. Two internasals and two prefrontals. Frontal as long as or slightly longer than its distance from tip of snout, as long as or slightly shorter than the parietals. 7-9 upper labials. Loreal pit not in contact with the upper labials.
Found in Nepal, Thailand, Cambodia, Laos, Vietnam, northern West Malaysia and on the Indonesian island of Java. The type locality is listed as "Java". There are unconfirmed, but credible reports from southern Myanmar (Burma), northern Sumatra and northern Borneo.
This species has a reputation for being bad-tempered and quick to strike. In northern Malaysia it is responsible for some 700 incidents of snakebite annually with a mortality rate of about 2 percent. Remarkably sedentary, it has often been found in the same spot several hours after an incident involving humans. Its venom causes severe pain and local swelling and sometimes tissue necrosis, but deaths are not common. Unfortunately many victims are left with dysfunctional or amputated limbs due to the lack of antivenom and early treatment.
- List of crotaline species and subspecies
- Crotalinae by common name
- Crotalinae by taxonomic synonyms
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