The variable colored vine snake (''Ahaetulla anomala'') is a species of

snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...

in the family

Colubridae Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on ever ...

. It is the first reported sexually dichromatic snake from the Indian Subcontinent, and until 2017 was formerly regarded as a subspecies 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. Distribution Due to longstanding confusion over the taxonomy of ''A. nasuta'', the specie ...

.''

Description

This species is

sexually dichromatic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most anim ...

. Males are green and resemble 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 tree snake endemic to Sri Lanka. Populations in the Western Ghats of India are now considered a separate species, ''Ahaetulla sahyadrensis''. It is known ...

'').

Distribution

It is limited to India (

Odisha Odisha (English: , ), formerly Orissa ( the official name until 2011), is an Indian state located in Eastern India. It is the 8th largest state by area, and the 11th largest by population. The state has the third largest population of ...

West Bengal West Bengal (, Bengali: ''Poshchim Bongo'', , abbr. WB) is a state in the eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabitants within an area of . West Bengal is the fourt ...

Jharkhand Jharkhand (; ; ) is a state in 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 and Odisha to the south. It has an area of . It ...

Bihar Bihar (; ) is a state in eastern India. It is the 2nd largest state by population in 2019, 12th largest by area of , and 14th largest by GDP in 2021. Bihar borders Uttar Pradesh to its west, Nepal to the north, the northern part of West Be ...

) and Bangladesh.

Characteristics

''Ahaetulla anomala'' shows color polymorphism and has a gradient of green and brown colour. Sexual dichromatism is rare among snakes and is mostly only documented in some groups such as vipers ('' Bothrops''), Comoran snakes (''

Lycodryas ''Lycodryas'' is a genus of snakes in the family Pseudoxyrhophiidae. The genus contains ten species, eight of which are endemic to the island of Madagascar, and two to the Comoros Islands. All of the species are harmless to humans. Species The ...

''), and Malagasy leaf-nosed snakes (''

Langaha madagascariensis ''Langaha madagascariensis'' (formerly ''Langaha nasuta'', commonly known as the Madagascar or Malagasy leaf-nosed snake) is a medium-sized highly cryptic arboreal species. It is endemic to Madagascar and found in deciduous dry forests and rain ...

'').

History

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 Government of India Ministry of Environment, Forest and Climate Change, as premier Indian organisation in zoological research and studies to promote the survey, exploration and r ...

) in 1906. For more than 100 years, its sexually dimorphic color scheme led to confusion of the females with the brown-speckled whipsnake and the males with the long-nosed whip snake. To resolve this confusion a team of biologists conducted molecular and morphological study of this snake, ultimately finding it to be a distinct species from both the long-nosed and brown-speckled whipsnakes. A 2020 study found ''A. anomala'' to be possibly conspecific with '' A. oxyrhyncha''.

References

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