  We present new stringent limits on the mass $M_{bh}$ of the central
supermassive black hole for a sample of 7 nearby galaxies. Our $M_{bh}$
estimates are based on the dynamical modeling of the central width of the
nebular emission lines measured over subarcsecond apertures with the Hubble
Space Telescope. The central stellar velocity dispersion $\sigma_c$ of the
sample galaxies is derived from new long-slit spectra from ground-based
observations and the bulge effective radius is obtained from a two-dimensional
photometric decomposition of the i-band images from the Sloan Digital Sky
Survey. The derived stringent $M_{bh}$ limits run parallel and above the
$M_{bh}-\sigma_c$ relation with no systematic trend depending on the galaxy
distance or morphology. This gives further support to previous findings
suggesting that the nuclear gravitational potential is remarkably well traced
by the width of the nebular lines when the gas is centrally peaked. With our
investigation, the number of galaxies with stringent $M_{bh}$ limits obtained
from nebular-line width increases to 114 and can be used for studying the
scaling relations between $M_{bh}$ and properties of their host galaxies.
