  Cosmological black holes (CBH), i.e. black holes with masses larger than
$10^{14} solar masses, have been proposed as possible progenitors of galaxy
voids (Stornaiolo 2002). The presence of a CBH in the central regions of a void
should induce significant gravitational lensing effects and in this paper we
discuss such gravitational signatures using simulated data. These signatures
may be summarized as follows: i) a blind spot in the projected position of the
CBH where no objects can be detected; ii) an excess of faint secondary images;
iii) an excess of double images having a characteristic angular separation. All
these signatures are shown to be detectable in future deep surveys.
