Common names: hump-nosed vipers, hump-nosed pit vipers.

Hypnale is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

s found in Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

 and southwestern India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. Three monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are currently recognized (no subspecies). All members have a more or less upturned snouts that produce a hump-nosed effect.

Description

Members of this genus grow to a maximum length of 55 cm (for H. hypnale

Hypnale hypnale

Hypnale hypnale is a venomous pitviper species found in India and Sri Lanka. No subspecies are currently recognized.-Description: Grows to an average of 30-45 cm in length. The Armed Forces Pest Management Board states 0.4-0.6 m in length....

). The body is stout, but relatively slender compared to most other crotalines

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

. The tail length account for 14-18% of total body length in males, 11-16% in females.

The snout is more or less upturned, with two species having a wartlike protuberance at the tip that is covered with tiny scales. The anterior head shields are strongly fragmented, but the frontal scale, supraoculars and parietals are complete and quite large. The nasal scale is single, but it may have a groove that extends towards its upper edge. There are two preoculars and 2-4 postoculars. The loreal scale is single, but extends across the canthus rostralis

Canthus (snake)

In snakes and amphibians, the canthus, canthal ridge or canthus rostralis, is the angle between the flat crown of the head and the side of the head between the eye and the snout. More specifically, between the supraocular scale and the rostral scale. It is defined as a sharp ridge in many viperids,...

 so that it can be seen from above. The supralabials and sublabials both number 7-9. Bordering the supralabials are 3-4 enlarged temporal scales

Temporal scales

In reptiles, the temporal scales are those scales on the side of the head between the parietal scales and the supralabial scales, and behind the postocular scales.There are two types of temporal scales:...

, above which are 3-5 irregular rows of temporal scales. There is one pair of chin shields, each of which is slightly longer than it is wide.

At midbody there are 17 rows of dorsal scales

Dorsal scales

In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...

, which are weakly keeled. Apical pits are present, but very difficult to see. The keels are lacking or may be entirely absent on the first two scale rows bordering the ventrals. The ventral scales

Ventral scales

In snakes, the ventral scales are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that contacts the paraventral row of dorsal scales on either side...

 number 120-158, while the subcaudals vary in number from 28-48 (almost all are paired).

Geographic range

Found in Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

 and India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, from almost sea level to an elevation of at least 1,829 m. In India they are found in the Western Ghats

Western Ghats

The Western Ghats, Western Ghauts or the Sahyādri is a mountain range along the western side of India. It runs north to south along the western edge of the Deccan Plateau, and separates the plateau from a narrow coastal plain along the Arabian Sea. The Western Ghats block rainfall to the Deccan...

 as far as 16° north latitude.

Habitat

They occur in dense jungles, dry forests, rain forests, both in low and hilly country, and in plantations. They sometimes are also found near or in human habitations.

Behavior

Mostly nocturnal, but are often seen coiled in the shade during the day, moving around on cloudy days, or under low light conditions. They are generally inoffensive, both in the wild and in captivity, rarely attempting to bite unless restrained or injured.

Species

Species	Taxon author	Common name	Geographic range
H. hypnale Hypnale hypnale Hypnale hypnale is a venomous pitviper species found in India and Sri Lanka. No subspecies are currently recognized.-Description: Grows to an average of 30-45 cm in length. The Armed Forces Pest Management Board states 0.4-0.6 m in length.... T	(Merrem Blasius Merrem Blasius Merrem was a German naturalist.Merrem was born at Bremen, and studied at the university of Göttingen under Johann Friedrich Blumenbach. He developed an interest in zoology, particularly ornithology... , 1820)	Hump-nosed viper	Peninsular India India India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...  to the Western Ghats as far north as 16° and Sri Lanka Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the... .
H. nepa Hypnale nepa Hypnale nepa is a venomous pitviper species found in Sri Lanka. Relatively small, they are distinguished by a strongly upturned snout. No subspecies are currently recognized.-Description:...	(Laurenti Josephus Nicolaus Laurenti Josephus Nicolaus Laurenti was an Austrian naturalist of Italian origin.Laurenti is considered the auctor of the class Reptilia through his authorship of on the poisonous function of reptiles and amphibians... , 1768)	Sri Lankan hump-nosed viper	In Sri Lanka throughout forsted areas, from lowland rainforest to over 1,800 m altitude.
H. walli Hypnale walli Hypnale walli is a venomous pitviper species found in Sri Lanka. The smallest member member of its genus, it is distinguished by having a strongly upturned nose and lower scale counts...	Gloyd Howard K. Gloyd Howard Kay Gloyd was an American herpetologist who is credited with describing several new species of reptile, such as the Florida Cottonmouth, Agkistrodon piscivorus conanti... , 1977	Wall's hump-nosed viper	Sri Lanka.

^T) Type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

.

Taxonomy

According to Gloyd and Conant (1990), members of this group seem to be closely related to the genus Calloselasma

Calloselasma

Calloselasma is a monotypic genus created for a venomous pitviper species, C. rhodostoma, which is found in Southeast Asia from Thailand to northern Malaysia and on the island of Java. No subspecies are currently recognized.-Description:...

.

External links

• Hypnale hypnale, image 1/2 at CalPhotos. Accessed 30 June 2007.
• Hypnale hypnale, image 2/2 at CalPhotos. Accessed 30 June 2007.