Fall relation colour coded according to the VMC method over-density estimate δ. Only galaxies located in rich groups with more than ten members are shown as circles (black squares correspond to field galaxies). The mass model rotation curve is used with the redshift cut (0.5 < z < 0.9) applied. As an indication, the best-fit linear relations (with only the redshift cut applied, see also Table 1) for the field and rich groups’ sub-samples with the stellar mass cut (M_⋆ < 10¹⁰ M_⊙) applied are shown as grey and black plain lines, respectively, and without the mass cut applied as grey and black dotted lines, respectively. The typical uncertainty is shown as the black error-bar.