Logarithm of the ratio between the average HI mass of dusty QGs and the equivalent HI contained at the same stellar mass in MS galaxies according to B25, plotted against the median overdensity δ for each galaxy bin. A dashed horizontal line at y = 0 indicates the HI content in SFGs. Purple filled squares mark the HI estimates from stacking dusty galaxies in lower-density (δ < 1) and in higher-density (δ > 1) bins, irrespective of morphology; shaded bands indicate uncertainties. Red and teal dotted lines indicate the HI estimate from stacking spirals and spheroids, respectively, irrespective of environment, spanning across the δ range.