Land Snail Diversity of Coastal Karnataka, India, and Effect of Physicochemical Parameters of the Environment on their Distribution

This study was designed to estimate the land snail diversity of coastal Karnataka, India, and to compare it with that of the Western Ghats mountain range. Altogether, 23 species of land snails were recorded, of which 18 species were found in coastal Karnataka and 3 species were confined only to Western Ghats. The highest number of land snails were found in national parks, followed by plantations, and the lowest in open areas. Rhachistia praetermissus was confined to the nagabana of Harekala and Rishetia sp. was only seen in home gardens. Among the plantations, land snail diversity was higher in arecanut plantations and lower in rubber plantations. Land snails such as Mariaella dussumieri and Macrochlamys indica were common to most of the visited habitats. Significant correlation between humidity and species richness of land snails indicates that humidity determines the land snail diversity in coastal Karnataka. Reserve forests/National Parks studied encompass more land snail diversity as they provide heterogeneous habitats and suitable ecological niches. Lower diversity of land snails in plantations and open areas compared to the reserve forests can be attributed to lower habitat complexity and anthropogenic disturbances.