Rhabdophis subminiatus

Rhabdophis subminiatus
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Colubridae
Genus:	Rhabdophis
Species:	R. subminiatus
Binomial name
Rhabdophis subminiatus (Schlegel, 1837)
Synonyms
Tropidonotus subminiatus Schlegel, 1837 Amphiesma subminiatum — A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854 Natrix subminiata — Barbour, 1912 Rhabdophis subminiatus — Bourret, 1936

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. The species is endemic to Asia. Unusual for snakes, it is also poisonous.

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, mating behavior multiple males may swarm a single female.

Habitat and diet

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

Snakebite and venom

Red-necked keelback from Nam Cat Tien National Park, South Vietnam.

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. Rear-fanged snakes need to bite and hold on, or repeatedly bite, to have any effect on humans. 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.

Extraction of snake venom from the red-necked keelback snake

Symptoms caused by venom

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 are involved with the front teeth and do not cause adverse effects, rare bites from the rear fangs can be lethal. Studies in mice on the biological activity of the venom of the red-necked keel-back snake, Rhabdophis subminiatus, showed that the venom contained a potent Factor X activator and had intense defibrinogenating activity; the overall proteolytic activity of the venom was low, and this correlated well with its negligible fibrinogenolytic and fibrinolytic activities. Only one antivenom tested was shown to have weak neutralizing activity against the venom in mice. This species of snake has recently been added to the schedule of the Dangerous Wild Animals Act, 1976.

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

The red-necked keelback can be found in:

• Bangladesh
• Indonesia (Sumatra, Borneo, Java, Sulawesi)
• Thailand, Vietnam, Cambodia, Laos, Burma
• Peninsular Malaysia
• Bhutan
• Nepal
• India ( Tripura, Assam, Meghalaya, West Bengal, Sikkim, Arunachal Pradesh, Mizoram, Nagaland )
• China (Yunnan, Guangxi, Guangdong, Fujian, Hong Kong, Hainan)

External links

• Media related to Rhabdophis subminiatus at Wikimedia Commons
• R. subminiatus Snakebite

Further reading

• Boulenger GA (1893). Catalogue of the Snakes in the British Museum (Natural History). Voume I., Containing the Families ... Colubridæ Aglyphæ, part. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (Tropidonotus subminiatus, pp. 256–257).
• Bulian J (1999). "Über die Schlangenfauna eines Gartens in Südthailand ". Elaphe 7 (4): 61-67. (in German).
• Das I (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books, 144 pp. ISBN 0-88359-056-5. (Rhabdophis subminiatus, p. 44).
• Schlegel H (1837). Essai sur la physionomie des serpens. Partie Générale. xxviii + 251 pp. + Partie Descriptive. 606 + xvi pp. Amsterdam: M.H. Schonekat. (Tropidonotus subminiatus, new species, pp. 313–314 in Partie Descriptive). (in French).
• Schmidt KP (1925). "New Reptiles and a New Salamander from China". American Museum Novitates (157): 1-5. (Natrix helleri, new species, p. 3).
• Smith MA (1943). The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Reptilia and Amphibia. Vol. III.—Serpentes. London: Secretary of State for India. (Taylor and Francis, printers). xii + 583 pp. (Natrix subminiata, pp. 302–303).