''Rhabdophis subminiatus'', commonly called the red-necked keelback or red-necked keelback snake, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

venomous snake ''Venomous snakes'' are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow ...

in the subfamily

Natricinae The Natricinae are a subfamily of colubroid snakes, sometimes referred to as a family (Natricidae). The subfamily comprises 36 genera. Members include many very common snake species, such as the European grass snakes, and the North American wa ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Colubridae Colubridae (, commonly known as colubrids , from , 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest fossil species of the family date back to the Late Eocene epoch, with earlier origins suspected. C ...

. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

. Unusual for colubrids, it is also poisonous. This snake is found mostly in terai and sivalik region in Nepal and locally called Deule tiris.

Description

''Rhabdophis subminiatus'' has a greenish hue with red and yellow regions near the head. It grows to 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

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

s 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

envenomation Envenomation is the process by which venom is injected by the bite or sting of a venomous animal. Many kinds of animals, including mammals (e.g., the northern short-tailed shrew, ''Blarina brevicauda''), reptiles (e.g., many snakes), spiders, i ...

s, the

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

of its

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

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 The Duvernoy's gland is a gland found in some groups of ''colubridae, colubrid'' snakes. It is distinguished from the venom gland and is not found in ''viperidae, viperids'' or ''elapidae, elapids''. It was named for France, French zoologist Geo ...

, 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 Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...

, including hemorrhaging of the brain, as well as

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

coagulopathy Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding ( bleeding diathesis), which may occur s ...

, and even

disseminated intravascular coagulation Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking Microvessel, small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems ...

. Also, when the venom was tested on animals,

kidney failure Kidney failure, also known as renal failure or end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney fa ...

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. 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 Coagulation factor X (), or Stuart factor, is an enzyme of the coagulation cascade, encoded in humans by ''F10'' gene. It is a serine endopeptidase (protease group S1, PA clan). Factor X is synthesized in the liver and requires vitamin K for i ...

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 Fibrinolysis is a process that prevents thrombus, blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the thrombolysis, breakdown of clots due to a medicine, a medical di ...

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 The Dangerous Wild Animals Act 1976 (c. 38) is an act of the Parliament of the United Kingdom. It was originally enacted to deal with the increasing fashion of people in the late-1960s and early-1970s keeping interesting pets which were often fr ...

, 1976. The snake consumes poisonous toads as part of its diet. It stores the bufotoxins from the consumed toads in its nuchal glands located at the red colorful region of the neck of the snake. Bufotoxins induce tachycardia, drooling, convulsions, and finally paralysis. When threatened such as by touching, the snake can burst its nuchal glands, releasing the stored toxin.

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 Edmund Heller (May 21, 1875 – July 18, 1939) was an American zoologist. He was President of the Association of Zoos & Aquariums for two terms, 1935–1936 and 1937–1938. Early life While at Stanford University, he collected specimens in the ...

. Schmidt, Karl P. (1925). "New reptiles and a new salamander from China". ''American Museum Novitates'' (157): 1-5. http://digitallibrary.amnh.org/dspace/handle/2246/9

Geographic range

The red-necked keelback can be found in: *

Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

(Sumatra, Borneo, Java, Sulawesi) *

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...

Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

Burma Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and ha ...

* Peninsular

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

Bhutan Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia, in the Eastern Himalayas between China to the north and northwest and India to the south and southeast. With a population of over 727,145 and a territory of , ...

Nepal Nepal, officially the Federal Democratic Republic of Nepal, is a landlocked country in South Asia. It is mainly situated in the Himalayas, but also includes parts of the Indo-Gangetic Plain. It borders the Tibet Autonomous Region of China Ch ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

(

Tripura Tripura () is a States and union territories of India, state in northeastern India. The List of states and union territories of India by area, third-smallest state in the country, it covers ; and the seventh-least populous state with a populat ...

Assam Assam (, , ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . It is the second largest state in Northeast India, nor ...

Meghalaya Meghalaya (; "the abode of clouds") is a states and union territories of India, state in northeast India. Its capital is Shillong. Meghalaya was formed on 21 January 1972 by carving out two districts from the Assam: the United Khasi Hills an ...

West Bengal West Bengal (; Bengali language, Bengali: , , abbr. WB) is a States and union territories of India, state in the East India, eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabi ...

Sikkim Sikkim ( ; ) is a States and union territories of India, state in northeastern India. It borders the Tibet Autonomous Region of China in the north and northeast, Bhutan in the east, Koshi Province of Nepal in the west, and West Bengal in the ...

Arunachal Pradesh Arunachal Pradesh (; ) is a States and union territories of India, state in northeast India. It was formed from the North-East Frontier Agency (NEFA) region, and India declared it as a state on 20 February 1987. Itanagar is its capital and la ...

Mizoram Mizoram is a states and union territories of India, state in northeastern India, with Aizawl as its Capital city, capital and largest city. It shares 722-kilometres (449 miles) of international borders with Bangladesh to the west, and Myanmar t ...

Nagaland Nagaland () is a States and union territories of India, state in the northeast India, north-eastern region of India. It is bordered by the Indian states of Arunachal Pradesh to the north, Assam to the west, Manipur to the south, and the Naga Sel ...

) *

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

(

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

Guangxi Guangxi,; officially the Guangxi Zhuang Autonomous Region, is an Autonomous regions of China, autonomous region of the China, People's Republic of China, located in South China and bordering Vietnam (Hà Giang Province, Hà Giang, Cao Bằn ...

Guangdong ) means "wide" or "vast", and has been associated with the region since the creation of Guang Prefecture in AD 226. The name "''Guang''" ultimately came from Guangxin ( zh, labels=no, first=t, t= , s=广信), an outpost established in Han dynasty ...

Fujian Fujian is a provinces of China, province in East China, southeastern China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, Guangdong to the south, and the Taiwan Strait to the east. Its capital is Fuzhou and its largest prefe ...

Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...

Hainan Hainan is an island provinces of China, province and the southernmost province of China. It consists of the eponymous Hainan Island and various smaller islands in the South China Sea under the province's administration. The name literally mean ...

)

References

External links

*
R. subminiatus Snakebite