Upper figure: r′-band magnitude histogram of the 783 fLSBs with available photo-zs. Lower figure: luminosity function for the 142 fLSBs with photo-z < 0.2 as a function of absolute r′-band magnitude (assuming these objects are cluster members). The vertical line shows the approximate completeness level of the fLSB sample derived from our simulations. The oblique line shows the mean slope of the luminosity function for absolute r′-band magnitude brighter than  − 12.9 (see text).