Boulenger's keelback

Boulenger's keelback[1] or Sri Lankan keelback,[3] (Fowlea asperrimus) is a nonvenomous and common water snake endemic to Sri Lanka.[4][5][6][7]

For the southeast Asian species called Boulenger's keelback, see Hebius boulengeri

Boulenger's keelback
Fowlea asperrimus
Taken by: Gunnar Pettersson(Wildlife Artist) at Sinharaja, Sri Lanka on 2008-02-19.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Fowlea
Species:
F. asperrimus
Binomial name
Fowlea asperrimus
(Boulenger, 1891)[1]
Synonyms

Tropidonotus asperrimus Boulenger, 1891:281
Tropidonotus asperrimus — Boulenger, 1893:232
Natrix piscator asperrimus — Smith, 1943[2]
Natrix asperrimus — Taylor 1950:567
Xenochrophis asperrimus — Das 1996:59
Xenochrophis asperrimus — Vogel & David 2006

Habitat
See also: Bundala National Park § Fauna

F. asperrimus is found in Sri Lanka,[8][9][10] in both dry and wet climatic zones up to 1000 m above mean sea level. It is abundant in waterways, such as flooded rice fields, ponds, lakes, marshes, rivers and streams.[1][5][11]

Characteristics

The body of F. asperrimus is short and cylindrical, and has a clear neck and slightly pointed head. The eyes have rounded pupils, and the nostrils are narrow, directed slightly upwards. The tail is long. At birth, they are 100 mm and grow to an adult length of 400–700 mm. The female is longer.[1][5][6]

Scales
See also: Snake scales § Nomenclature of scales

It has one pair of internasals; the posterior parts are narrow. One loreal, preocular, postocular and three temporals are found. Of the 9 supralabials, 4 and 6 connect with the eye. Ventrals number 131–146, and the undividedsubcaudals are 73–93 in count. The midbody consists of 19 rows of scales. The dorsal scales are strongly keeled and rough.[12][1][6][11][13]

Colour

The dorsal body color of F. asperrimus 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 strips run behind the eyes. The ventral body is white. It can be easily identified by dark spots or bars on the first half of the body and two dark lines behind the eyes.[1][5]

Behavior

Boulenger's keelback is oviparous, diurnal and nocturnal. In dry conditions during the summer, it undergoes aestivation. It is active in water bodies in search of its prey, which consist mainly of fish and frogs. It is known to be very aggressive. When threatened, it attempts to bite, by flattening its head and neck as does the cobra. The bite may cause wounds. Also, it may release noxious odor.[1][5]

Breeding

The gestation period 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.[1][5][11]

Common names

References
  1. Boulenger, G.A. (1891). "Description of new oriental reptiles and batrachians". Annals and Magazine of Natural History. Taylor and Francis, Ltd. London. 6: 279–283.
  2. Smith, M.A. (1943). "3. Serpentes". The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-Region. Reptilia and Amphibia. Taylor and Francis, Ltd. London. p. 583.
  3. Bambaradeniya, Channa N. B. & Sri Lanka, IUCN (2006). The Fauna of Sri Lanka: Status of Taxonomy, Research, and Conservation. IUCN. p. 156. ISBN 9789558177518. LCCN 9558177512.
  4. Das, I. & De Silva, A. (2005). Photographic guide to snakes and other reptiles of Sri Lanka. New Holland Publishers. p. 144.
  5. Suranjan Karunarathna, D. M. S. & Thasun Amarasinghe, A. A. (2011). "A Preliminary Survey of the Reptile Fauna in Nilgala Forest and its Vicinity, Monaragala District, Sri Lanka". Taprobanica. 3 (2): 69–76.
  6. Taylor, Edward H. (1950). "The snakes of Ceylon". University of Kansas Science Bulletin. 33 (14): 519–603. ISSN 0022-8850.
  7. Fowlea asperrimus at the Reptarium.cz Reptile Database. Accessed 19 January 2016.
  8. Beolens, Bo; Watkins, Michael & Grayson, Michael (2011). The Eponym Dictionary of Reptiles. JHU Press. pp. 33–35. ISBN 9781421401355. LCCN 1421401355.
  9. De Silva, A. (1998). "Snakes of Sri Lanka: a checklist and an annotated bibliography". Dept. Wildlife Conservation/GEF/UNDP/FAO, Colombo. Cite journal requires |journal= (help)
  10. Wall, Frank (1921). Ophidia Taprobanica or the Snakes of Ceylon. Colombo Mus. (H. R. Cottle, govt. printer), Colombo. p. 581.
  11. Boulenger, G.A. (1893). "Catalogue of the snakes in the British Museum.(Natural history) Vol. I". Taylor and Francis, London: 448. Cite journal requires |journal= (help)
  12. Vogel, G. & David, Patrick (2006). "On the taxonomy of the Xenochrophis piscator complex (Serpentes, Natricidae)" (PDF). Herpetologica Bonnensis. II: 241–246.
  13. Janzen, P.; Klaas, P. & Ziesmann, S. (2007). "Sri Lankas Schlangenfauna". Draco. 7 (30): 56–64.
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