The role of beak shape in octopodid taxonomy

Beak shapes in nine species of Southern Ocean octopodids were measured using seven size-standardized ratios. The results were analysed using principal component analysis and discriminant function analysis and show that beak shape may be used as a taxonomic character to distinguish between genera, but not between species. Stepwise discriminant function analysis indicated that all seven ratios were required to maximize discrimination between beaks. A phenogram constructed from a matrix of Mahalanobis distances differed from a dendrogram produced from genetic data. This suggests that, although useful for discrimination, beak morphology is probably not suitable for constructing phylogenies.