The distribution of the genus Lanistes includes Africa and Madagascar.
Description
Lanistes has a unique anatomy among the Ampullariidae: it has a "hyperstrophic" sinistral shell. This means that the body of the snail is dextral (as in all other ampullariids), but the shell appears to be sinistral. However the sinistral appearance stems from the fact that the rotation of the shell as it grows is in an upward direction rather than the usual downward direction.
Species
Three subgenera have been recognized, based on shell differences: Lanistes sensu stricto, Meladomus and Leroya. These subgenera are not used in recent works.
1234567891011van Damme D. & Pickford M. (1995). "The late Cenozoic ampullariidae (mollusca, gastropoda) of the Albertine Rift Valley (Uganda-Zaire)". Hydrobiologia316(1): 1-32. doi:10.1007/BF00019372.
Schultheiß R., Van Bocxlaer B., Wilke T. & Albrecht C. (2009). "Old fossils–young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi". Proceedings of the Royal Society B276(1668): 2837-2846. doi:10.1098/rspb.2009.0467.