Study of morphological variation discernible by multivariate analysis between the species of genus Setipinna (Teleostei: Clupeiformes)

Abstract

In order to correctly identify and differentiate three similar species of genus Setipinna namely Setipinna tenuifilis, S. taty and S. phasa, samples were collected from the coast of West Bengal, India. Twenty-four morphometric traits were measured. The morphometric data were subjected to factor analysis and discriminant analysis, which satisfactorily differentiated these species. Analysis of variance (ANOVA) carried out for twenty-three morphometric ratios showed a significant difference between the species for all the considered variables. Higher F-ratio (>200) for dorsal fin base length, anal fin base length, pectoral fin filament length, length from the tip of snout to anal fin, anal fin to dorsal fin length and maximum body depth signifies their role in species separation either alone or combination with other morphometric characters. Stepwise discriminant function analysis included nine log transformed morphometric ratios emphasizing their taxonomic significance, with length from the tip of snout to anal fin, dorsal fin base length, maximum body depth and pectoral fin filament length, as the most important discriminating characters. SDFA gave correct classification in 100% cases with no instances of misclassification. Squared Mahalanobis distance showed relative distinctness of S. phasa from the other two members of the genus. The scatterplot of the canonical scores of all the specimens for Root 1 and Root 2 showed clear demarcation between the species in the form of separate clusters. Further, selected 14 meristic features showed significant ability to discriminate among the species.