Checkered keelback

{{Speciesbox

| name = Checkered keelback

| image = Checkered Keelback Xenochrophis piscator Schneider, 1799 Assam by Dr Raju Kasambe DSC 0477 (2).JPG

| image_caption = in Assam

| status = LC

| status_system = IUCN3.1

| status_ref = {{Cite journal | author = Stuart, B.L., Wogan, G., Thy, N., Nguyen, T.Q., Vogel, G., Srinivasulu, C., Srinivasulu, B., Shankar, G., Mohapatra, P., Thakur, S. & Papenfuss, T. | name-list-style = amp | title = Fowlea asperrimus | journal = The IUCN Red List of Threatened Species | volume = 2021 | page = e.T172646A1358305 | publisher = IUCN | date = 2021 | url = https://www.iucnredlist.org/species/172646/1358305 | access-date = 15 January 2021}}

| genus = Fowlea

| species = piscator

| authority = (Schneider, 1799)

| synonyms = {{collapsible list|bullets = true|title=List

|Hydrus piscator
{{small|Schneider, 1799}}

|Natrix piscator
{{small|— Merrem, 1820}}

|Tropidonotus quincunciatus
{{small|Schlegel, 1837}}

|Tropidonotus piscator
{{small|— Boulenger, 1893}}

|Nerodia piscator
{{small|— Wall, 1921}}

|Xenochrophis piscator
{{small|— Cox et al., 1998}}

}}

| synonyms_ref = {{EMBL species|genus=Xenochrophis|species=piscator}}. www.reptile-database.org.

| range_map =

| range_map_caption =

}}

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

Description

File:Fowlea piscator 86567565.jpg]]

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.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).

The checkered keelback is a medium-sized snake, but may grow to be large. Adults may attain a snout-to-vent length (SVL) of {{convert|1.75|m|ft|abbr=on}}.

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. Though it is non-venomous to humans, it can deliver a painful bite which is inflammatory.

F. piscator may lose its tail as an escape mechanism. A rare case of such autotomy is reported from Vietnam.Ananjeva NB, Orlov NL (1994). "Caudal Autotomy in Colubrid Snake Xenochrophis piscator From Vietnam"

Russian Journal of Herpetology 1 (2): 169-171.File:Checkered Keelback at Khulna.jpg, Khulna, Bangladesh]]File:Checkered keelback at Taudaha, kathmandu.jpg]]File:Xenochrophis piscator - Checkered Keelback at Palappuzha (5).jpg]]

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 {{convert|1.5|-|4.0|cm|in|abbr=on}} long. The female guards the eggs until they hatch. Each hatchling is about {{convert|11|cm|in|abbr=on}} long.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).

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, Australia and Indonesia (Sumatra, Java, Borneo, Celebes = Sulawesi)

type locality: "East Indies".

Subspecies

F. p. melanzostus {{small|(Gravenhorst, 1807)}} – Indonesia (Borneo [?], Java, Sulawesi [?]; Sumatra), India (Andaman and Nicobar Islands)
F. p. piscator {{small|(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.

Gallery for identification characteristics

File:Char1 Nostril.JPG|Chart 1 - Nostrils directed slightly upwards

File:Char2 Frontal.JPG|Chart 2 - Frontal constricted in the middle, twice as long as broad

File:Char3 Internasals.JPG|Chart 3 - Internasals much narrowed anteriorly, nearly as long as the prefrontals

File:Char4 Preocular.JPG|Chart 4 - One preocular scale only

File:Char5 Temporals.JPG|Chart 5 - Temporals are 2+2 or 2+3

File:Char6 Supralabials.JPG|Chart 6 - 9 supralabials, 4th and 5th touching the eye, the 6th excluded by the lowest postocular

File:Char7 Stout body.JPG|Chart 7 - Body rather stout

File:Char8 Small tail.JPG|Chart 8 - Small tail

File:Char9 19scales.JPG|Chart 9 - Scales in 19 distinct rows

File:Body Xenochrophis piscator.JPG|Body of checkered keelback

File:Checkered-keelback in IIT Bombay.JPG

File:Checkered Keelback.jpg|Checkered keelback basking

File:Xenophis piscator gab fbi.png|Scale pattern