Geometric Morphometric Analysis of the Chinese Mitten Crab Eriocheir sinensis: A Potential Approach for Geographical Origin Authentication

The illegal counterfeiting of the geographic origin label for Chinese mitten crabs Eriocheir sinensis is a major problem in China. More effective methods are needed for authenticating their geographic origin and increasing their commercial value. Therefore, a geometric morphometric analysis was conducted for the present pilot study to identify variation in Chinese mitten crabs from eight well-known geographic areas in China: Gehu, Luoma, Gucheng, Liangzi, and Junshan lakes in the Yangtze River system; the Dongying area in the Yellow River system; and the Yingkou and Panjin areas in the Liaohe River system. Landmark coordinates were extracted by image processing after digitization of the carapace and the ventral region of the cephalothorax and were then analyzed using relative warp principal components methods, discriminant analysis, thin-plate spline analysis, and grid distortion. Many of the type II landmarks used were extracted via relative warp principal components analysis, and they had the most important contributions to explaining the variation. The discriminant analysis indicated that the carapace of male and female crabs and the ventral region of the cephalothorax in males had geographical origin distinguishing rates of 100%. These results suggest that plasticity in shape exists for local adaptation of the ventral region of the cephalothorax and especially the carapace among Chinese mitten crabs from the different locations examined. Geometric morphometric analysis has potential for authenticating the important commercial crab species by authorized inspectors or scientists in markets or laboratories after further development of image processing, landmark extraction, shape morphometric databases, detection models, and geographical origin recognition.