Distribution

Sri Lanka and the southern region of the Western Ghats in India. See link "Distribution" at the top of the page for detailed information.


  Map 61 Hypnale spp.

Biology

The three species are difficult to distinguish from each other. As with Calloselasma rhodostoma and Deinagkistrodon acutus they were previously included among the genus Agkistrodon, and their appearance is very similar to those species. Clearly distinct, triangular, flat head. Tapering snout; H. nepa has a wart-like protuberance on the tip of the snout. Colouring and markings are very variable, with basic shades of light to dark grey or brown, sometimes with small, dark, semicircular blotches along the spine.

Predominantly ground-dwelling and nocturnal. H. hypnale is the largest species but barely reaches more than 50 cm. It is very common in Sri Lanka and inhabits the most varied climate zones. It lives primarily in forests and grasslands as well as in different agricultural areas (rubber, coffee, tea, coconut, cocoa, cashew and banana plantations), at altitudes of up to 1,250 m above sea level. H. nepa in rainforests and in other forests, restricted to the higher elevations of SriLankas central mountains. H. zara in the in the south western wet zone lowlands of Sri Lanka. Hypnale hypnale is tremendously threatened by anthropogenic pressure in the state of Goa, India and maybe also in neighbouring states of the Western Ghats (Sawant et al. 2010). A major impact seems to be made by habitat loss and fragmentation due to mining activities.

During the day they often lie under leaf litter, fallen wood or stones. When threatened they coil their body, vibrate the tip of their tail and raise their upper body slightly. From this defensive position, H. hypnale in particular strikes without hesitation.

Risk

Fatalities very rare. H. hypnale, as the most dangerous species of its genus, causes the majority of venomous snakebites in Sri Lanka. H. hypnale bites can cause not only local effects, as is common with H. nepa, but also severe systemic effects (Warrell, pers. comm.).

Literature (biological)

Gloyd and Conant 1989, Gumprecht et al. 2004, De Silva 1990, Maduwage et al. 2009, Sawant et al. 2010, Whitaker and Captain 2015

The Reptile Database