The morphological evolution of an initially straight stripe assimilated to a straight line of infinite length lying on a semi-infinite substrate has been investigated in the linear regime when the mass transport mechanism is the diffusion of adatoms along stripe edges and when the heteroepitaxy between the line and the substrate is taken to be anisotropic. It is found that contrary to the isotropic case where serpentine-like morphology is favored, antiphase fluctuations grows faster than in-phase ones for selected values of epitaxial stress components such that a pinched shape preferentially emerges.