H₂-to-Hi ratio against stellar mass surface density (left panel), metallicity (central panel), and ratio of dust to stellar mass (right panel). Virgo SFDs (blue dots) are compared to spiral (grey squares) and irregular-peculiar (red triangles) galaxies from the HRS. Hi-deficient galaxies in all samples are indicated with empty symbols. The dotted line in the central panel shows the scaling relation obtained for the HRS galaxies with a normal Hi content (Boselli et al. 2014c).