Relative Warp and Correlation Analysis based on Distances of the Morphological shell shape patterns among freshwater gastropods (Thiaridae: Cerithimorpha)

Shell morphology has various details in their architecture that contributes effectively togastropod identification and classification. A conventional approach has been made to study shellmorphology using descriptions of biological shapes. However, descriptions can be strengthened byapplying additional quantitative tools. Relative Warp Analysis and Correlation Analysis based onDistances (CORIANDIS) were used to determine shell shape divergence and ascertain factorsassociated with the shell shape variation in three species of the genus Melanoides of the familyThiaridae namely, Melanoides granifera, Melanoides maculate, and unknown Melanoides speciesbelonging to the family Thiaridae. Relative warp summarizes the vectors of shape variation withinsamples. CORIANDIS on the other hand, examines similarities among samples and interpreted interms of congruence among traits. Results of the relative warp analysis showed significant shellshape variation among the Thiaridae species in the height of the spire, aperture, and apical shapes.Distance matrices were also constructed for the three data sets of shell characters: ventral/aperture,dorsal, and top/whorl shell. Results of the comparison via correlation analyses of distances among thespecies showed that an unknown Melanoides species is closely related to M. maculate than M.granifera. The results of the present study clearly show the importance of geometric morphometricanalysis determination of systematic relationship in Thiarid snails.