Checkered keelback

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Checkered keelback
Checkered Keelback Xenochrophis piscator Schneider, 1799 Assam by Dr Raju Kasambe DSC 0477 (2).JPG
Xenochrophis piscator, in Assam
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Xenochrophis
Species:
X. piscator
Binomial name
Xenochrophis 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 (Xenochrophis 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.

X. piscator, swimming in Kerala

Description[edit]

The eye of X. 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 is 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 cross bands, 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[edit]

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

Habitat[edit]

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

Diet[edit]

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

Reproduction[edit]

X. 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.[edit]

X. 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[edit]

  • X. p. melanzostus (Gravenhorst, 1807) – Indonesia (Borneo [?], Java, Sulawesi [?]; Sumatra), India (Andaman and Nicobar Islands)
  • X. 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 Xenochrophis.

Taxonomy[edit]

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

Local names[edit]

Gallery for identification characteristics[edit]

References[edit]

  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).
  3. ^ a b 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.

Further reading[edit]

  • Boulenger GA (1893). Catalogue of the Snakes in the British Museum (Natural History).Volume I., Containing the Families ... Colubridæ Aglyphæ, part. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (Tropidonotus piscator, pp. 230-232).
  • Dutt, Kalma (1970). "Chromosome Variation in Two Populations of Xenochrophis piscator Schn. from North and South India (Serpentes, Colubridae)". Cytologia 35: 455–464.
  • Schneider JG (1799). Historiae Amphibiorum naturalis et literariae. Fasciculus Primus, continens Ranas, Calamitas, Bufones, Salamandras et Hydros. Jena: F. Frommann. xiii + 264 pp. + corrigenda + Plate I. (Hydrus piscator, new species, pp. 247-248). (in Latin).
  • Smith MA (1943). The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Amphibia and Reptilia. Vol. III.—Serpentes. London: Secretary of State for India. (Taylor and Francis, printers). xii + 583 pp. (Tropidonotus piscator, pp. 293-296, Figures 95-96).

External links[edit]