Systematics, diversity, and origins of upper cretaceous continental molluscan fauna in the infra- and intertrappean strata of the Deccan Plateau, central India

The Deccan Plateau in western and central India has been a major area of interest for researchers since the 1800s. In 1840, James Sowerby described the molluscan collection sent to him by John Malcolmson. In 1860, Stephen Hislop identified new molluscan species and redescribed based on better preserved material. Although this seminal work was comprehensive, interpretations have changed since the mid 1800s. Species need to be reassigned to current and/or accurate taxa, as well as revalidated statistically. Seventeen character traits were measured on over 600 specimens from five eastern Deccan Plateau localities representing a stratigraphic and temporal sequence. Cluster analysis was utilized to observe grouping patterns among specimens including Deccan type specimens and modern related species. Three new species (Lymnaea pokhariensis, Bellamya lattooformis, and Zootecus burji) and four new subspecies (Tricula conoidea conoidea, T. c. hislopi, Valvata unicarinifera unicarinifera, and V. u. chiknaformis) were identified and described. Three families with their associated genera and one genus (Viviparidae to Pomatiopsidae, Viviparidae to Subulinidae, Physidae to Planorbidae, and Viviparus to Bellamya) were revised to accommodate a more accurate taxonomic and biogeographic framework. Analysis of Variance (ANOVA) was employed to look at changes in morphology through the sequence and χ2 tests were used to observe changes in diversity and abundance. Overall, there is a dramatic decrease in species size with the onset of volcanism but morphology and diversity remain stable. Species abundance changes but the lack of pattern suggests it is not a result of the volcanism