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International Journal of Zoology and Applied Biosciences Research Article
Allometric constancy in Physa prinsepii morphotypes from the deccan intertrappean beds, India
Anubarna Dutta Chowdhury, Dola Roy, Debjani Nandi, Dhriti Banerjee
Year : 2026 | Volume: 11 | Issue: 1 | Pages: 303-309
Received on: 11/11/2025
Revised on: 27/12/2025
Accepted on: 13/01/2026
Published on: 31/01/2026
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Anubarna Dutta Chowdhury, Dola Roy, Debjani Nandi, Dhriti Banerjee( 2026).
Allometric constancy in Physa prinsepii morphotypes from the deccan intertrappean beds, India
. International Journal of Zoology and Applied Biosciences, 11( 1), 303-309.
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Abstract
The freshwater gastropod Physa prinsepii Sowerby, 1840 from the Late Cretaceous–Early Paleogene Deccan Intertrappean beds of central India has been subdivided into three subspecies (Physa prinsepii normalis, Physa prinsepii elongata, and Physa prinsepii inflata) based on shell morphology. We conducted morphometric analysis of 194 specimens from multiple intertrappean localities of Madhya Pradesh to reassess this taxonomic subdivision. Our bivariate analysis reveals a remarkably consistent linear allometric relationship (slope ≈ 1.4–1.5) between shell height and width across all morphotypes, spanning specimens from 3 mm to 45 mm in width and 3 mm to 68 mm in height. All morphotypes exhibit substantial overlap along a common regression trajectory with no discrete clusters in morphospace. The constant allometric coefficient across morphotypes indicates they do not represent genetically differentiated lineages but rather ecophenotypic variants within a single plastic species. These morphotypes likely represent adaptive responses to variable environmental conditions in the Deccan volcanic landscape, including fluctuating water depth, flow regime, calcium availability, and predation pressure. Our findings support treating normalis, elongata, and inflata as environmentally induced morphotypes rather than formal subspecies, demonstrating the importance of phenotypic plasticity in gastropod survival during periods of extreme environmental instability.
Keywords
Allometry, Ecophenotypic plasticity, Gastropoda, Late Cretaceous.
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© The Author(s) 2025. This article is published by International Journal of Zoology and Applied Biosciences under the terms of the Creative Commons Attribution 4.0 International License (creativecommons.org), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
