Thai National Parks

Species of Thailand

Checkered keelback

Fowlea piscator

(Johann Gottlob Theaenus Schneider, 1799)

In Thai: งูลายสอใหญ่, ngu lai sor yai

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

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.

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.

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.

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 long. The female guards the eggs until they hatch. Each hatchling is about 11 cm long.

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 – Indonesia (Borneo , Java, Sulawesi ; Sumatra), India (Andaman and Nicobar Islands)
  • F. p. piscator – 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.

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Scientific classification

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Suborder
Serpentes
Family
Colubridae
Genus
Fowlea
Species
Fowlea piscator

Common names

  • German:
    • Gewöhnliche Fischnatter
    • Fischernatter
  • English:
    • Asiatic water snakes
    • Checkered keelback
  • Thai:
    • งูลายสอใหญ่, ngu lai sor yai
    • งูสา, ngu saa

Subspecies

  • Xenochrophis piscator melanzostus, Johann Ludwig Christian Gravenhorst, 1807

    Range: Indonesia (Borneo Java, Sulawesi?, Sumatra), India (Andaman and Nicobar Islands).

  • Xenochrophis piscator piscator, Johann Gottlob Theaenus Schneider, 1799

    Range: Bangladesh, Bhutan, India, Myanmar, Pakistan, People's Republic of China (including Hainan), Sri Lanka, Taiwan and Thailand.

Synonyms

  • Fowlea tytleri, Chandramouli (2022)
  • Fowlea piscator, Thasun Amarasinghe et al. (2022)
  • Fowlea tytleri, Thasun Amarasinghe et al. (2022)
  • Xenochrophis piscater (in error),  BHANDARKAR & PALIWAL (2021)
  • Fowlea piscator, Jayaditya Purkayastha et al. (2019)
  • Natrix piscator, Ramesh Singh et al. (2016)
  • Xenochorpis piscator, Fellows (in error) (2015)
  • Xenochrophis piscator, Van Stanley Bartholomew Wallach et al. (2014)
  • Xenochrophis piscator, T.S.N. Murthy (2010)
  • Xenochrophis piscator, Tanya Chan-Ard et al. (1999)

Conservation status

Least Concern (IUCN 3.1)

Least Concern (IUCN 3.1)

Photos

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Fowlea piscator
Fowlea piscator
Xenochrophis piscator (head)
Xenochrophis piscator
Xenochrophis piscator (ready to shed)
Xenochrophis piscator

Range Map

Distribution map of Checkered keelback, Fowlea piscator in Thailand
  • Bang Khen District, Bangkok
  • Doi Inthanon National Park
  • Doi Saket District, Chiang Mai
  • Hang Dong District, Chiang Mai
  • Hua Hin District, Prachuap Khiri Khan
  • Huai Kha Khaeng Wildlife Sanctuary
  • Kaeng Krachan National Park
  • Khao Yai National Park
  • Khun Tan District, Chiang Rai
  • Ko Chang District, Trat
  • Kui Buri National Park
  • Mae On District, Chiang Mai
  • Mae Ramat District, Tak
  • Mae Sariang District, Mae Hong Son
  • Mae Sot District, Tak
  • Mae Taeng District, Chiang Mai
  • Mueang Chiang Mai District, Chiang Mai
  • Mueang Lampang District, Lampang
  • Na Haeo District, Loei
  • Nam Nao National Park
  • Nang Rong District, Buriram
  • Pak Thong Chai District, Nakhon Ratchasima
  • Pang Sida National Park
  • Phu Kradueng National Park
  • Phu Luang Wildlife Sanctuary
  • Sai Yok District, Kanchanaburi
  • Sakaerat Environmental Research Station
  • Salawin National Park
  • San Sai District, Chiang Mai
  • Song District, Phrae
  • Suan Phueng District, Ratchaburi
  • Tha Song Yang District, Tak
  • Tha Yang District, Phetchaburi
  • Thung Chang District, Nan
  • Thung Yai Naresuan Wildlife Sanctuary
  • Umphang District, Tak
Range map of Fowlea piscator in Thailand