Resumen de Regional and intraspecific variation in Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae) morphology from the western central Pacific Ocean
Bilin Liu, Hang Su, Peng Zhang, Xinjun Chen
Regional and intraspecific variation in eight morphometric characters are described for the purpleback flying squid, Sthenoteuthis oualaniensis (Lesson, 1830 in 1830–1831), from the Bashi Channel and South China Sea. Principal components analysis indicated statistically significant sexual dimorphism for medium forms, but not for the dwarf form. Additionally, principal components analysis using mantle length standardized morphometric variables had considerable overlap, with a correct sex classification rate of <65%. Stepwise discriminant analysis revealed overall correct cross-validated classification rates of only 48.0% for the three squid forms from the Bashi Channel and South China Sea. The lack of significant intraspecific differences in squid from the same area indicates that the underlying cause of morphometric variation is environmental rather than phylogenetic. Finally, the relatively low cross-validated classification rates (<70%) indicate that using morphometric data alone to distinguish the focal sexes and forms is of limited practical utility, and that other types of data, such as genetic or hard tissue morphometrics, hold greater promise.
