Checkered keelback

Checkered keelback
	in Assam
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Colubridae
Genus:	Fowlea
Species:	F. piscator
Binomial name
	Fowlea piscator; (Schneider, 1799)
Synonyms[1]
	Hydrus piscator ; Schneider, 1799; Natrix piscator ; — Merrem, 1820; Tropidonotus quincunciatus ; Schlegel, 1837; Tropidonotus piscator ; — Boulenger, 1893; Nerodia piscator ; — Wall, 1921; Xenochrophis piscator ; — Cox et al., 1998;

The checkered keelback (Fowlea piscator), also known commonly as the Asiatic water snake, is a common species of nonvenomous snake in the subfamily Natricinae of the family Colubridae. The species is endemic to Asia.

Swimming in Kerala

Checkered keelback at Taudaha, kathmandu

Description

The eye of F. piscator is rather small and shorter than its distance from the nostril in the adult. Its rostral scale is visible from above. The internasal scales are much narrowed anteriorly and subtriangular, with the anterior angle truncated and as long as the prefrontal scales. The frontal scale is longer than its distance from the end of the snout, and as long as the parietals or a little shorter. The loreal is nearly as long as it is deep. There are one preocular and three (rarely four) post-oculars. Its temporals are 2+2 or 2+3. There are normally nine upper labials, with the fourth and fifth entering the eye; and five lower labials in contact with the anterior chin-shields, which are shorter than the posterior. The dorsal scales are arranged in 19 rows, strongly keeled, with outer rows smooth. The ventrals number 125–158, the anal is divided, and the subcaudals number 64–90. Coloration is very variable, consisting of dark spots arranged quincuncially and often separated by a whitish network, or of black longitudinal bands on a pale ground, or of dark crossbands, with or without whitish spots. Two oblique black streaks, one below and the other behind the eye, are nearly constant. The lower parts are white, with or without black margins to the shields.[2]

The checkered keelback is a medium-sized snake, but may grow to be large. Adults may attain a snout-to-vent length (SVL) of 1.75 m (5.7 ft).[3]

Defensive behavior

Most of the time this snake tries to raise its head as much as possible and expand its neck skin mimicking a cobra hood and intimidate the threat.

F. piscator may lose its tail as an escape mechanism. A rare case of such autotomy is reported from Vietnam.[4]

Habitat

The preferred habitat of F. piscator is in or near freshwater lakes or rivers.

Diet

F. piscator feeds mainly on small fish and water frogs.

Reproduction

F. piscator is oviparous. Clutch size is usually 30-70 eggs, but may be as few as 4 or as many as 100. Egg size is also variable. Each egg may be 1.5–4.0 cm (0.59–1.57 in) long. The female guards the eggs until they hatch. Each hatchling is about 11 cm (4.3 in) long.[3]

Geographic range.

F. piscator is found in Afghanistan, Bangladesh, Pakistan, Sri Lanka, India, Myanmar, Nepal, Thailand, Laos, Cambodia, Vietnam, West Malaysia, China (Zhejiang, Jiangxi, Fujian, Guangdong, Hainan, Guangxi, Yunnan), Taiwan, and Indonesia (Sumatra, Java, Borneo, Celebes = Sulawesi)

type locality: "East Indies".

Subspecies

F. p. melanzostus (Gravenhorst, 1807) – Indonesia (Borneo [?], Java, Sulawesi [?]; Sumatra), India (Andaman and Nicobar Islands)
F. p. piscator (Schneider, 1799) – Bangladesh, Bhutan, India, Myanmar, Pakistan, People's Republic of China (including Hainan), Sri Lanka, Taiwan, and Thailand

Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Fowlea.

Taxonomy

The subspecies F. p. melanzostus was raised to species status, as Fowlea melanzostus, by Indraneil Das in 1996.

Local names

Mizo – tui rul
Assamese – ঢোঁৰা সাপ
Bengali – জল ডোরা সাপ
Odia – ଧଣ୍ଡ ସାପ
Gujarati – dendu saap
Hindi – dendu saap
Indonesia – bandotan tutul
Kannada – ನೀರು ಹಾವು
Marathi – दिवड
Malayalam – നീർക്കോലി
Tamil – கண்டங்கண்டை நீர்க்கோலி (kandangkandai neerkoli)
Telugu – నీరు కట్టే (neeru katte)
Bihari – dhoriya saap
Nepali – dhode/dhoriya saap
Chinese (Traditional Chinese) – "漁游蛇"
Chinese (Simplified Chinese) – "渔游蛇"
Sinhalese - "දිය බරියා"

Gallery for identification characteristics

Chart 1 - Nostrils directed slightly upwards
Chart 2 - Frontal constricted in the middle, twice as long as broad
Chart 3 - Internasals much narrowed anteriorly, nearly as long as the prefrontals
Chart 4 - One preocular scale only
Chart 5 - Temporals are 2+2 or 2+3
Chart 6 - 9 supralabials, 4th and 5th touching the eye, the 6th excluded by the lowest postocular
Chart 7 - Body rather stout
Chart 8 - Small tail
Chart 9 - Scales in 19 distinct rows
Body of checkered keelback
Checkered keelback basking
Scale pattern

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References

Species Xenochrophis piscator at The Reptile Database . www.reptile-database.org.
Boulenger GA (1890). The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. London: Secretary of State for India in Council. (Taylor and Francis, printers). xviii + 541 pp. (Tropidonotus piscator, pp. 349-350).
Das I (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books. 144 pp. ISBN 0-88359-056-5. (Xenochrophis piscator, p. 48).
Ananjeva NB, Orlov NL (1994). "Caudal Autotomy in Colubrid Snake Xenochrophis piscator From Vietnam" Russian Journal of Herpetology 1 (2): 169-171.

External links

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[1] Species Xenochrophis piscator at The Reptile Database . www.reptile-database.org.

[2] Boulenger GA (1890). The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. London: Secretary of State for India in Council. (Taylor and Francis, printers). xviii + 541 pp. (Tropidonotus piscator, pp. 349-350).

[Das2002-3] Das I (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books. 144 pp. ISBN 0-88359-056-5. (Xenochrophis piscator, p. 48).

[4] Ananjeva NB, Orlov NL (1994). "Caudal Autotomy in Colubrid Snake Xenochrophis piscator From Vietnam" Russian Journal of Herpetology 1 (2): 169-171.