imply very different chronologies; the Gondwanan vicariance hypothesis implies that proto-Indoplanorbis has been present in India since the late Eocene (35 Ma; India: Asia collision), whereas dispersal via the Sinai-Levant suggests a Plio-Pleistocene arrival. The results by Liu et al. (2010) indicated a radiation beginning in the late Miocene with a divergence of an ancestral bulinine lineage into Assam and peninsular India clades. A Southeast Asian clade diverged from the peninsular India clade late-Pliocene; this clade then radiated at a much more rapid pace to colonize all of the sampled range of Indoplanorbis in the mid-Pleistocene. Description The shell of this species, like all planorbids is sinistral in coiling, but is carried upside down and thus appears to be dextral. The shell of Indoplanorbis exustus is discoid with rapidly increasing whorls. Each whorl is higher than it is wide. The width of the shell is 5–25 mm. The height of the shell is 4.5–13 mm. Planorbella duryi and Biomphalaria pfeifferi have similar shells. Because of its wide distribution, various aspects of Indoplanorbis exustus have been studied, such as its calcium regulation and its hemocytes. Ecology In captivity Indoplanorbis exustus can be reared on lettuce and spinach. Its diet is sometimes supplemented with sheep's liver and it can be given rat food to prepare for breeding. Habitat The snail is found in small ponds, pools, and less commonly in rice paddy fields. The snail may also occur in semi-permanent pools formed in flooded areas of fields, where it can survive the dry season buried in mud. The desiccation tolerance of adult snails is high, while the resistance of juvenile snails is very low. Consequently, dispersal may occur in clumps of mud adhered to the bodies of cattle or across water in vegetation mats. It is possible it could be transported by birds. Life cycle Indoplanorbis exustus is a hermaphroditic invasive snail species with high fecundity. Within one year of introduction the snail is able to colonize habitats with well established populations of other pulmonate and prosobranch snails. The snail requires a water temperature in excess of 15 °C for maturation. At the optimum temperature of 30 °C each snail can lay up to 800 eggs. There is from 2 to 43 eggs in one cluster with an average 20 eggs in one cluster. The capacity for self-fertilization and high fecundity probably underlies the invasive potential of the species. The average life