The variable colored vine snake (''Ahaetulla anomala'') 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), ...

opisthoglyphous A snake skeleton consists primarily of the skull, vertebrae, and ribs, with only vestigial remnants of the limbs. Skull The skull of a snake is a very complex structure, with numerous joints to allow the snake to swallow prey far larger than it ...

(rear-fanged

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 ...

ous)

colubrid 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. Colu ...

vine

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

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 ...

and

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 ...

. It is the first reported

sexually dichromatic Sexual dimorphism is the condition where sexes of the same species exhibit different morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecious species, which consis ...

snake from the Indian Subcontinent, and until 2017 was formerly regarded as a

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the green vine snake, ''

Ahaetulla nasuta ''Ahaetulla nasuta'', also known as Sri Lankan green vine snake and long-nosed whip snake, is a venomous, slender green tree snake endemic to Sri Lanka. It was previously known as the common green vine snake and was widely distributed across Indi ...

.''

Taxonomy

This snake was first described by

Thomas Nelson Annandale Thomas Nelson Annandale CIE FRSE (15 June 1876, in Edinburgh – 10 April 1924, in Calcutta) was a British zoologist, entomologist, anthropologist, and herpetologist. He was the founding director of the Zoological Survey of India. Life The eld ...

(the first director of the

Zoological Survey of India The Zoological Survey of India (ZSI), founded on 1 July 1916 by the Ministry of Environment, Forest and Climate Change of the Government of India as a premier Indian organisation in zoological research and studies to promote the survey, explora ...

) in 1906. It was later considered a

of ''

'' in 1943. There has long been

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

confusion due to the sexually dimorphic coloring of species, with the green males resembling the long-nosed whip snake (''

''), while females are brown in color and physically resemble the brown-speckled whipsnake (''

Ahaetulla pulverulenta Brown-speckled whipsnake or brown vine snake (''Ahaetulla pulverulenta'') is a species of colubrid vine snake Endemism, endemic to Sri Lanka. Etymology It is known as හෙනකදයා (''henakadaya'') in Sinhalese language, Sinhala; this ...

''). To resolve this confusion, in 2017, a team of biologists conducted a molecular and morphological study of the snake, ultimately finding it to be a distinct species, closely related to its

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

'', as shown in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below (with possible

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

species noted): The status of ''Ahaetulla anomala'' as a separate species is still in dispute, as a 2020 study found ''A. anomala'' to be possibly

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organism ...

with '' Ahaetulla oxyrhyncha''.

Distribution

It is limited to India (

Odisha Odisha (), formerly Orissa (List of renamed places in India, the official name until 2011), is a States and union territories of India, state located in East India, Eastern India. It is the List of states and union territories of India by ar ...

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 ...

Jharkhand Jharkhand (; ) is a States and union territories of India, state in East India, eastern India. The state shares its border with the states of West Bengal to the east, Chhattisgarh to the west, Uttar Pradesh to the northwest, Bihar to the north ...

Bihar Bihar ( ) is a states and union territories of India, state in Eastern India. It is the list of states and union territories of India by population, second largest state by population, the List of states and union territories of India by are ...

) and

Description

This species is

, with the males being green, while females are brown in color. Sexual dichromatism is rare among snakes and is mostly only documented in some groups such as

vipers Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous and have long (relative to non-viper ...

(''

Bothrops ''Bothrops'' is a genus of highly venomous pit vipers Endemism, endemic to the Neotropics.McDiarmid RW, Jonathan A. Campbell, Campbell JA, Touré T. 1999. ''Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1''. Herpetologist ...

''), Comoran snakes ('' Lycodryas''), and Malagasy leaf-nosed snakes ('' Langaha madagascariensis''). It has rear fangs typical of the ''

Ahaetulla ''Ahaetulla,'' commonly referred to as Asian vine snakes or Asian whip snakes, is a genus of colubrid snakes distributed throughout tropical Asia. They are considered by some scientists to be mildly venomous and are what is commonly termed as 'r ...

'' genus, and a long prominent appendage at the tip of its snout, covered by many small scales above, which is unique among related species. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

was long in total body length.

Behavior

The snake is diurnal and

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

, and mostly found on shrubs, trees, and bushes. It feeds primarily on lizards, and it is

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...

References

{{Taxonbar, from=Q30085217 Reptiles described in 1906 anomala Snakes of Asia Taxa named by Nelson Annandale