Upper panel: residuals of Li 6708 EW with respect to mean locus vs. B − V defined by IC 2391 members plotted versus rotational period (dashed line in Fig 8). Filled and open (black) circles: IC 2391 stars with confirmed+likely and uncertain rotation periods, respectively; filled and open (blue) squares: Argus field stars, with confirmed+likely and uncertain rotation periods, respectively; (red) star: HD 61005. The continuous line represents the fit of IC 2391 members with confirmed rotational periods, and the dotted line represents the fit including the unconfirmed periods. Lower panel: residuals of Li 6708 EW with respect to mean locus vs. B − V defined by IC 2391 members plotted versus projected rotational velocity. Filled circles: IC 2391. Filled squares: Argus field. (Red) star: HD 61005.