Upper panel: relationship between the number of HII regions of luminosity L(Hα) > 10³⁷ erg s⁻¹ and the stellar mass of galaxies. Blue symbols indicate gas-rich systems (HI-def ≤ 0.5), red symbols HI-stripped galaxies (HI-def > 0.5). Empty symbols represent bulge-dominated Sa-Sab galaxies. The dashed blue and red lines give the bisector fits for gas-normal and gas-stripped systems. Lower panel: relationship between the residual of the above relation derived for HI-rich galaxies and the HI-deficiency parameter. Symbols are colour-coded in ranges of stellar mass: M_star >  10^9.5 M_⊙ – dark green, 10⁸ <  M_star ≤ 10^9.5 M_⊙ – magenta, 10^6.5 <  M_star ≤ 10⁸ M_⊙ – cyan. Dots are for HI-detected galaxies, triangles for HI-undetected objects (lower limits in the HI-deficiency parameter). ρ_s is the Spearman correlation coefficient.