Geographic Variation and Subspecific Status of Notropis spilopterus (Pisces: Cyprinidae)

Two nominal subspecies are recognized in the literature for the spotfin shiner, Notropis spilopterus (Cope). Gibbs (1957b) differentiated a western subspecies, N. s. hypsisomatus, from the eastern, N. s. spilopterus primarily on the basis of number of lateral line scales and body depth. Evidence presented in this study indicates that these subspecies are invalid. The variation in number of lateral line scales is essentially an east-west dine with no discontinuity. A total of 358 specimens from 16 localities throughout the range were examined for 27 morphometric characters using a truss system of measurement and entered into a principal component analysis using the shear technique. Scatter plots of component scores along PC I and sheared PC II revealed large overlap between population samples and discordant patterns of geographic variation. Discriminant analysis correctly classified only 61% of the western and 68% of the eastern subspecies on the basis of geographic locality. The lack of a non-arbitrary discontinuity in the observed pattern of variation supports the synonymy of N. s. hypsisomatus with N. s. spilopterus.