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

of water

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 ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Colubridae 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. C ...

. The species is

endemic Endemism is the state of a species being found only 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 foun ...

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

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 a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level ...

. 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 , : 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 turbinates, ...

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 which is Latin f ...

, postocular 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 of the United States and Canada''. Comstock Publishing Associates, a Division of Cornell University Press. (7t ...

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 The fus ...

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 reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, diurnal and

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

. In dry conditions during the summer, it undergoes

aestivation Aestivation ( (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 a lowered m ...

. 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 behavior aimed at opposing or attacking something or someone. Though often done with the intent to cause harm, some might channel it into creative and practical outlets. It may occur either reactively or without provocation. In h ...

. When threatened, it attempts to bite, by flattening its head and neck as does the

cobra COBRA or Cobra, often stylized as CoBrA, was a European avant-garde art group active from 1948 to 1951. The name was coined in 1948 by Christian Dotremont from the initials of the members' home countries' capital cities: Copenhagen (Co), Brussels ...

. 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 i ...

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: Culture, language and peoples * ''English'', an adjective for something of, from, or related to England * ''English'', an Amish ter ...

: Boulenger's keelback or Sri Lankan keelback * Sinhalese: 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