An Illustrated Guide to the Land Snails of Sri Lankan Natural Forest and Cultivated Habitats provides a brief introduction to the land-snail faunas of the major natural forest types of the island and of the main dry land (i.e. not subjected to seasonal flooding) cultivated habitats. For the purposes of this laminated fold-out guide the land-snail fauna of submontane and montane rainforest have been treated as a single grouping under the habitat type 'submontane/montane rainforest'.
Most of Sri Lanka's land-snail diversity is concentrated in two forest types: lowland rainforest and submontane/montane rainforest. The land-snail faunas of these two forest types are for the most part quite distinct. Most lowland rainforest snails do not occur in submontane/montane rainforest, and most submontane/montane rainforest species are not found in lowland rainforest. The land-snail faunas of lowland and submontane/montane rainforest are essentially a mixture of widespread species (species that occur across most or all of the geographical range of a single forest type) and restricted-range species (species restricted to a discrete and often much smaller part of the entire geographical range of a single forest type). For example, Acavus phoenix is widespread in the lowlands of the wet zone (below an elevation of 1000 m), but the related species Acavus haemastoma only occurs in the southern part of the wet zone.
Dry monsoon forest, in contrast to rainforest, has relatively low land-snail diversity, with most species being wide-spread across the forests of the dry zone and also occurring in the moist monsoon forests of the intermediate zone. The land-snail fauna of moist monsoon forest is more diverse than that of dry monsoon forest, but is not as rich as that of rainforest. However, moist monsoon forest, like rainforest, contains both widespread and restricted-range snails. Due to its position between the rainforests of the wet zone and the dry monsoon forests of the dry zone, moist monsoon forest contains examples of both lowland rainforest snails and dry monsoon forest species.
Also included is a brief description of the distribution and composition of the major land-snail communities of the island. Only a representative selection of the more common or distinctive species in each of the five habitat categories is included in An Illustrated Guide to the Land Snails of Sri Lankan Natural Forest and Cultivated Habitats. Note that although some species occur in two or more of the major habitat types, they are illustrated under the habitat category with which they are most closely associated. Several of the species illustrated are new to science, are in the process of being formally described or are of uncertain taxonomic status. Such snails are simply referred to by their generic name e.g. Theobaldius sp.