Species delineation of lizardfishes, Saurida pseudotumbil Dutt and Sagar, 1981 and Saurida tumbil (Bloch, 1795) using multivariate tools

Abstract

Morphometric characters of two species of lizardfishes viz.,Saurida pseudotumbil Dutt and Sagar, 1981 and Saurida tumbil (Bloch, 1795), were studied  to delineate the species using multivariate techniques. Specimens were collected from Parangipettai and Cochin waters, southern India, for recording data on 21 morphometric characters. Principal component analysis (PCA) was done after log transformation and the first three components explained 93.36% of the total variation. The most important morphometric characters determined using the eigenvectors (coefficients) of these components were post-orbital length, snout to pectoral, snout to pelvic, snout to anal, anal fin base and dorsal fin base, which showed high loading (≥0.8) in the three components. The overlapping ratio between these species ranged from 42.59 to 89.28%. The PCA data cloud of S. pseudotumbil and S. tumbil also reflected the same trend. Therefore, canonical analysis of principal coordinates (CAP) was done which clearly separated the species with maximum case allocation success (100%) for both S. pseudotumbil and S. tumbil, which clearly showed that both the species are different.