Exploring Natricine Snakes in Sri Lanka

Abstract

The nuchal glands are unique organs embedded under the skin of the neck region, in 13 species of natricine snakes distributed from Southeast Asia, Japan, China, to South Asia. In Sri Lanka, of the presently known 105 species of snakes (including marine forms), the two species, which possess nuchal glands are: Balanophis ceylonensis (Gunther, 1858) and Macropisthodon plumbicolor palabariya Deraniyagala, 1955. Balanopltis ceylonensis B. ceylonensis, is a lowland rain forests species, found among moist leaf litter, underneath decaying logs. It has been recorded from many localities in the wet (1) and intermediate (2) climatic zones up to an altitude of 600 m above the mean sea level. It is a small snake growing to a length of 415 to 610 mm. Feed on frogs and small reptiles. At dusk they are active and may observe crossing gravel roads. Its ecology and habits are poorly known. The hemipenis is bifid with spines at the apex. A specimen collected in January 2014 from Yagirala forest contained five well formed eggs, suggesting that it may lay during March/ April. Although it is a docile snake, when cornered it may slightly inflate its neck region. We have come across four bites by Balanophis. Of these, on 21.1.2014 a young man who got bitten on the hand, developed systemic envenoming symptoms. It's posterior fangs are large and broadly canalized. Macropisthotlon plumbicolor palabariya Deraniyagala, 1955 The species name plumbum from Latin meaning 'lead', the color of the ventral aspect. However, in Sri Lanka we have come across this colour on the ventral aspect only in a few specimens and all others had pearly white belly. When cornered, it raises its fore body and expands the neck region like the cobra, giving rise to one of its common names, "green cobra". M. plumbicolor, is a forest and grassland species and also found in plantations like tea and in anthropogenic habitats. It is found among moist leaf litter, underneath decaying logs etc. it has been recorded from many localities in the wet (1) intermediate (2) and dry (2) climatic zones up to an altitude of about 700 m above the mean sea level. It is a docile snake, several handled by us and other herpetologists confirm that it never attempted to bite. However, Fletcher (1908), reports of a man who had pinched M. plumbicolor who accidentally rubbed his eyes afterwards had a very bad eyes for some days. It lay about 10-20 eggs in February/March/ April.