Boulenger's keelback (''Fowlea asperrima''), also known commonly as the Sri Lankan keelback, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of water

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 Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

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 ...

. The species 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 elsew ...

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

Etymology

The common name "Boulenger's keelback" is in honour of Belgian-born British herpetologist

George Albert Boulenger George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botani ...

Habitat

''F. asperrima'' is found in Sri Lanka, in both dry and wet climatic zones up to

above mean sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The comb ...

. It is abundant in waterways, such as flooded rice fields, ponds, lakes, marshes, rivers and streams.

Characteristics

The body of ''F. asperrima'' is short and cylindrical, and has a clear neck and slightly pointed head. The eyes have rounded pupils, and the

nostrils A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

are narrow, directed slightly upwards. The tail is long. At hatching, it is long and grows to an adult length of . The female is longer.

Scalation

''F. asperrima'' has one pair of

internasals In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates. (7 ...

; the posterior parts are narrow. One loreal,

preocular In scaled reptiles, the ocular scales are those forming the margin of the eye.Wright AH, Wright AA. 1957. ''Handbook of Snakes''. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . The name originates from the term ''oculus'' which ...

postocular In scaled reptiles, the ocular scales are those forming the margin of the eye.Wright AH, Wright AA. 1957. ''Handbook of Snakes''. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . The name originates from the term ''oculus'' which ...

and three temporals are found. Of the 9

supralabials In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scaleWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates ( ...

, 4 and 6 connect with the eye.

Ventrals In snakes, the ventral scales or gastrosteges 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 cont ...

number 131–146, and the undivided

subcaudals In snakes, the subcaudal scales are the enlarged plates on the underside of the tail.Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . These scales may be either single or divided (pair ...

are 73–93 in count. At midbody there are 19 rows of

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...

, which are strongly keeled and rough.

Colour

The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

body colour of ''F. asperrima'' is olive brown. The anterior half of the body has 20–32 distinct large black spots or cross bars. The posterior body may lack them or may be in light-colored irregular shapes. The head is dark in color. Two black lines run diagonally from behind the eyes to the corners of the mouth. Ventrally, the body is white. ''F. asperrimus'' can be easily identified by dark spots or bars on the first half of the body and two dark lines behind the eyes.

Behaviour

''F. asperrima'' is

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

, diurnal and

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

. In dry conditions during the summer, it undergoes

aestivation Aestivation ( la, aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and ...

. It is active in water bodies in search of its prey, which consist mainly of fishes and frogs. It is known to be very

aggressive Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reacti ...

. When threatened, it attempts to bite, by flattening its head and neck as does the cobra. The bite may cause wounds. Also, it may release a noxious odor.

Breeding

The

gestation period In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it ...

of ''F. asperrima'' is 55–67 days. Females do not guard the clutches of eggs, but they stay close to the nest. They lay clutches of four to 30 eggs between September and October.

Common names

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

Boulenger Boulenger is a surname. Notable people with the surname include: * Benjamin Boulenger (born 1990), French footballer * Edward George Boulenger (1888–1946), British zoologist, director of aquarium at London Zoo * George Albert Boulenger (1858–1 ...

's keelback or Sri Lankan keelback *

Sinhalese Sinhala may refer to: * Something of or related to the Sinhalese people of Sri Lanka * Sinhalese people * Sinhala language, one of the three official languages used in Sri Lanka * Sinhala script, a writing system for the Sinhala language ** Sinha ...

: දිය බරියා/දිය නයා

References

External links

Boulenger's keelback (''Xenochrophis asperrimus'')

''Xenochrophis asperrimus'' (Boulenger's keelback)
{{Taxonbar, from=Q2710705 Fowlea Reptiles of Sri Lanka Endemic fauna of Sri Lanka Reptiles described in 1891 Taxa named by George Albert Boulenger