Red-necked Keelback

Rhabdophis subminiatus, commonly called the red-necked keelback or red-necked keelback snake, is a species of venomous snake in the subfamily Natricinae of the family Colubridae. Unusual for colubrids, it is venomous.

Etymology

The specific name subminiatus refers to the typical reddish coloration ("miniatus" = "scarlet, vermilion"), which may be limited to the neck, or more extensive (e.g., photo at left). The subspecific name, helleri, is in honor of American zoologist Edmund Heller.

Geographic range

Rhabdophis subminiatus is restricted to the Indonesian islands of Java and Sumatra. Historically the species was considered to have a much wider distribution, but this changed when it was realized that the species was actually a species complex.

Description

Rhabdophis subminiatus has a greenish hue with red and yellow regions near the head. It grows to 70 to 90 cm (27.5 to 35.5 in) in total length (including tail). Female is much larger than male. During mating, multiple males may swarm a single female.

Habitat and diet

The red-necked keelback generally lives near ponds, where it consumes frogs, fish, lizards and small mammals.

Venom and poison

Rhabdophis subminiatus is a rear-fanged species and was previously thought to be harmless. However, following one fatal and several near-fatal envenomations, the toxicity of its venom was investigated. As a result, it has recently been reclassified as a dangerous species. In general, rear-fanged snakes need to bite and hold on, or repeatedly bite, to have any effect on humans. But recently, there have been reports of cases where even brief bites have resulted in severe envenomation and organ failure, affecting the kidneys and liver. A chewing action facilitates envenomation, as the venom ducts open to fangs that are externally grooved (not hollow) and are posterior in the oral cavity. R. subminiatus has enlarged and ungrooved teeth. The species has two enlarged teeth in the back of the jaw. Located in the upper jaw is a gland known as Duvernoy's gland, which produces an extremely venomous secretion.

Symptoms caused by venom and poison

When the snake bites, the salivary venom mixture is not injected, but it flows into the punctures produced by the upper jaw's rear teeth, which can penetrate the skin of humans. The venom from R. subminiatus has been responsible for internal hemorrhaging, including hemorrhaging of the brain, as well as nausea, coagulopathy, and even disseminated intravascular coagulation. Also, when the venom was tested on animals, kidney failure was reported. Caution should be taken when dealing with patients who have been bitten by the red-necked keelback snake. No further injury such as injections should be used because this may cause excessive bleeding in the bite victim. Although most bites of humans from R. subminiatus involve the front teeth and do not cause adverse effects, rare bites from the rear fangs can be lethal.