G-band versus RV period-amplitude ratios for the TQS sources classified as LPVs. Black contour lines represent a smoothed density map of the sample, and correspond to the black histograms on the sides of each panel. Each source is color-coded according to whether its period is identified as resulting from pulsation (red) or as an LSP (green). The same color-code is used for the histograms on the sides (normalized to their maximum). In the bottom panel the quantity log(A_G/P_G) is replaced with its distance from the dashed line displayed in the top panel, taken as an arbitrary reference.