摘要：The white-clawed crayfish Austropotamobius pallipes is a threatened European crayfish. Our purpose is to provide traits on the anterior portion of the carapace by geometric morphometrics describing landmarks poorly or not affected by ontogeny and sexual dimorphism. In this study, 112 crayfish (59 females and 53 males) from a central Italy brook were studied. A digital picture of dorsal side of each specimen was taken and then analysed according to a least-square method by the Generalized Procrustes Analysis that allowed the size to be standardised and to optimise rotation and translation of the configuration, after the fixation of 18 2D landmarks. In this study, we found no features affected by sexual dimorphism, while a certain percentage of morphological differences were observed only between juveniles and adults. These differences can be explained by positive and negative allometry, and interpreted as a direct effect of growth. The most evident of these changes regards the carapace enlargement and the ocular socket departure. Then, as size increases, there is relative shortening of the rostrum–carapace end line, displaying a negative allometry of this area, and narrowing of the lateral size of the carapace, overall in the infraorbital area. Our results show that in A. pallipes allometry is an important aspect in ontogeny of the carapace anterior portion. Further studies including several populations could be carried out in order to find morphological features characterizing each crayfish population.
