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Atretium | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Serpentes |
Family: | Colubridae |
Genus: | Atretium Cope, 1861 |
Species: | A. schistosum |
Binomial name | |
Atretium schistosum (Daudin, 1803) | |
Atretium schistosum, also known commonly as the split keelback and the olive keelback wart snake, is a species of snake in the subfamily Natricinae of the family Colubridae. The species, which is the sole species in the genus Atretium, is native to South Asia. It is a common and harmless watersnake.
A. schistosum is found in Sri Lanka, India, Bangladesh and Nepal. In India it occurs in peninsular India south of latitude 15 degrees north and along the east coast to Uttarakhand. It is reported to be very common around Bangalore, North Arcot district (Tamil Nadu) and Kakinada area in Andhra Pradesh. Occurs up to 1000 m (3280 ft) above sea level. Absent from most of North India.
A. schistosum is a small, robust snake with thin head, short snout and slit nostrils placed rather high. The snake is olive-green and yellow to orange below. It is sometimes tinged with pink or purplish on the flanks. The length of the tail is one third to one-fourth of the total length.
The dorsal scales are rough because they are keeled. Specimens from South India have a distinct reddish line along the 5th and 6th or the 4th and 5th up to the vent. This line is brighter in the males. The females are between 70 and 75 cm long, and the males between 50 and 60 cm. The longest measured snake is 87 cm long.
A. schistosum is distinguished by a number of scale characteristics:
It can easily be confused with olive forest snake ( Rhabdops olivaceus ).
A. schistosum lives in water or among the surrounding vegetation.
A diurnal snake, it is seen at night also. The snake rarely bites when handled. It is known to aestivate in the summer.
The olive keelback feeds mainly on frogs, tadpoles, fish and crabs which it catches with a side-stroke motion that is characteristic of watersnakes. The snake swims past the prey and suddenly snaps its head to the side. The olive keelback is also known to eat mosquito larvae (Whitaker).
Sometimes, referred to as a water-cobra, the olive keelback is nevertheless tolerated by people.
A. schistosum is oviparous (egg laying). It breeds in the monsoon. The eggs, which are white, soft and 30–35 mm (1.2–1.4 in) in length, are laid in clutches of 10 to 32 in the months January to April. The newly hatched snakes measure 16.6–17.5 cm (6.5–6.9 in) in length.
Echis carinatus, known as the saw-scaled viper, Indian saw-scaled viper, little Indian viper, and by other common names, is a viper species found in parts of the Middle East and Central Asia, and especially the Indian subcontinent. It is the smallest member of the "big four" Indian snakes that are responsible for causing the most snakebite cases and deaths, due to various factors including their frequent occurrence in highly populated regions, and their inconspicuous nature. Like all vipers, the species is venomous. Two subspecies are currently recognized, including the nominate subspecies described here.
Hypnale is a genus of pit vipers endemic to Sri Lanka and southwestern India. Three monotypic species are currently recognized. All members have more or less upturned snouts that produce a hump-nosed effect.
The buff striped keelback is a species of nonvenomous colubrid snake found across Asia. It is a typically non-aggressive snake that feeds on frogs and toads. It belongs to the subfamily Natricinae, and is closely related to water snakes and grass snakes. It resembles an Asian version of the American garter snake. It is quite a common snake but is rarely seen.
Boiga forsteni, also known commonly as Forsten's cat snake, is a species of mildly venomous rear-fanged snake in the family Colubridae. The species is endemic to South Asia.
The trinket snake, also known commonly as the common trinket snake, is a species of nonvenomous constricting snake in the family Colubridae. The species is native to southern Central Asia.
Gerarda prevostiana, commonly known as the cat-eyed water snake, Gerard's water snake, and the glossy marsh snake, is a species of snake in the family Homalopsidae. The species is endemic to Asia. It is the only species in the genus Gerarda.
Rhabdophis plumbicolor, known as the green keelback or lead keelback, is a species of nonvenomous snake in the family Colubridae native to parts of the Indian subcontinent.
The checkered keelback, 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.
Trimerodytes percarinatus, commonly known as the eastern water snake, olive keelback, olive annulate keelback or Chinese keelback water snake, is a species of snake in the subfamily Natricinae.
The Haly's tree skink is a species of lizard in the family Scincidae. The species is native to Sri Lanka. Earlier thought to be found also in the Western Ghats, taxonomic studies have shown D. haliana to be a Sri Lankan endemic, differentiated from the Indian D. subcaeruleum. D. haliana is the only arboreal skink in Sri Lanka.
Stokes's sea snake is a large species of sea snake in the family Elapidae. It is sometimes placed in its own genus Astrotia. The species is endemic to tropical Indo-Pacific oceanic waters.
Jerdon's sea snake is a species of venomous sea snake in the subfamily Hydrophiinae of the family Elapidae. The species is native to the Indian Ocean.
The spine-bellied sea snake, also commonly known as Hardwicke's sea snake and Hardwicke's spine-bellied sea snake, is a species of venomous sea snake in the family Elapidae. The species is native to the Indian Ocean and the western Pacific Ocean.
Hydrophis cantoris, also known commonly as Cantor's narrow-headed sea snake and Cantor's small-headed sea snake, is a species of venomous sea snake in the family Elapidae.
Craspedocephalus trigonocephalus, the Sri Lankan pit viper, Ceylon pit viper, Sri Lankan green pitviper or locally, pala polonga, is a venomous pit viper species endemic to Sri Lanka. No subspecies are currently recognized.
Rhinophis blythii, or Blyth's earth snake, is a species of snake in the family Uropeltidae. The species is endemic to the rain forests and grasslands of Sri Lanka.
Boulenger's keelback, also known commonly as the Sri Lankan keelback, is a species of water snake in the family Colubridae. The species is endemic to Sri Lanka.
Rhabdophis ceylonensis is endemic to the island of Sri Lanka. The species is commonly known as the Sri Lanka blossom krait, the Sri Lanka keelback, and මල් කරවලා or නිහලුවා (nihaluwa) in Sinhala. It is a moderately venomous snake.
Aspidura copei, commonly known as Cope's rough-sided snake or කලු මැඩිල්ලා in Sinhalese, is a species of snake in the family Colubridae. The species is endemic to Sri Lanka.
Aspidura drummondhayi, commonly known as Drummond-Hay's rough-sided snake or කෙටිවල් මැඩිල්ලා in Sinhala, is a species of snake in the family Colubridae. The species is endemic to Sri Lanka.