Résumé:
Our study is part of a Analysis based on landmark of the ‹‹marbled crab››Pachygrapsus marmoratus (Fabricus, 1787). We sampled 72 individuals from three stations: Salamander (SL), Sidi Medjdoub (SM) and Sidi Lakhdar (SK). Each individual was photographed in dorsal view for the purpose of performing the morphometric study, and then measured [Length (L),Width (R), Height (H) and Inter-Ocular Distance (Io)]. Other parameters such as the ratios H/L,L/R and Io/R were added together with the geometric mean (GM) to perform a biometric study. The PCA based on the L/R, H/L,Io/R and (GM) parameters showed us that the thicker the carapace is (H/L higher values) and the more it becomes rectangular (L/R low values). In addition, the correlation between (GM) and the two H/L and L/R ratios showed that there were several stages of carapace development involving individuals of different size. The CVA based on the coordinates of 27 landmark fixed on the back of the carapaces of P. marmoratus showed us that there was a morphometric dissmilarity between the populations of the three stations SL, SM and SK separating them into three distinct groups. In addition, there is a sexual dimorphism that may be related to the biological role of P. marmoratus females such as incubation of eggs. Finally, Ward's classification based on the coordinates of the landmark showed us that hydrodynamism could have an important role in the connectivity between different P. marmoratus populations of the coast Mostaganem.
