Skull shape variation among Xenopus taxa

FABREZI, MARISSA

Stellenbosch, South Africa

Congreso; Fifth World Congress of Herpetology; 2005

University of Stellenbosch

Shape is defined by integration of morphological features.  Usually, differentiation of taxa is expressed in terms of different morphological traits but not by shape. However, we can describe and differentiate a given taxon by reference to aspects of its form (e.g., by describing that the skull is acuminated or rounded).  Morphological interspecific differences among Xenopus taxa correspond to a limited set of quantitative characters that sometimes are not useful for distinguishing species, and size of mature specimens or locality may be tools to provide a preliminary identification.  In this study, an analysis of geometric variation of skull shape in a sample of six Xenopus taxa (X. laevis laevis, X. l. victorianus, X. fraseri, X. wittei, X. vestitus, and X. muelleri) has been carried out in order to assess: 1) shape variation related to size to determine whether any shape characteristics divide small from large taxa, 2) intraspecific variability in skull shape, and 3) taxa in which osteological variation is integrated in a distinctive form. This study has been conducted using thin-plate spline morphometric analyses on a sample of 120 Xenopus skulls.  Features of skull shapes that could be useful to aid taxonomic diagnosis and evaluate morphological variation in the genus Xenopus are discussed.