''Proahaetulla'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

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 ev ...

. It contains only one species, the keeled vine snake (''P. antiqua''), which is

endemic Endemism is the state of a species being found 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 found els ...

to the Western Ghats of

India India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...

. Its natural habitat is montane rainforests of southern Western Ghats. The species was first discovered in 2011, when an individual was found in the

Agasthyamalai Hills The Pothigai Hills, also known as Agasthiyar Mountain is a 1,866-metre (6,122 ft)-tall peak in the southern part of the Western Ghats of South India. The peak lies in Tirunelveli District of Tamil Nadu near the border of Kerala. The ar ...

Tamil Nadu Tamil Nadu (; , TN) is a state in southern India. It is the tenth largest Indian state by area and the sixth largest by population. Its capital and largest city is Chennai. Tamil Nadu is the home of the Tamil people, whose Tamil languag ...

and

Kerala Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South C ...

. It was initially thought to be a new species of ''

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 're ...

'', as it looked very similar to the species '' A. dispar''. However, genetic analyses found it to be deeply divergent from any member in the genus ''Ahaetulla'', so it was classified in its own genus. Both the genus and species were ultimately described in 2019.

Taxonomy

It is considered to be the

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 ...

to the genus '' Ahetulla'', which it diverged from during the mid-

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

. Due to its age, ''Proahaetulla'' may be one of the oldest monotypic lineages of snakes to still persist in the Western Ghats. The study that described ''Proahaetulla'' also found that the clade containing it and ''Ahaetulla'' was a sister group to the genus '' Dryophiops''. ''Proahaetulla'' is also the first deeply divergent snake genus to be described from the Western Ghats in over a century; numerous Indian snake species have had new genera created to reclassify them from the genera they were originally classified in, but ''Proahaetulla'' is completely new, possibly having never been encountered by science prior to its description as a new genus and species.

Description

Dorsal scales smooth and arranged in 15 rows at midbody;strongly keeled in the sacral region of males. Two loreals, 1st in contact with the nasals. Ventrals 196-207; subcaudals 160-165; anal plate divided. Dorsally light green and two yellowish lateral lines present; very similar in appearance to

Ahaetulla dispar ''Ahaetulla dispar'', the Gunther's vine snake, is a species of tree snake endemic to the Western Ghats. It is primarily restricted to the Shola forests of the Southern Western Ghats where it is found often on high-elevation montane grassland ...

. Ventral colouration whitish or greenish. Total length 1200mm.

Habits and Distribution

It is a diurnal and semi-arboreal species found in the high elevation evergreen forests and grasslands of Western Ghats.

References

{{Taxonbar, from=Q84156843 Colubrids Snakes of Asia Reptiles of India Endemic fauna of the Western Ghats Reptiles described in 2019 Proahaetulla