  An electric charge near the surface of a topological insulator (TI) induces
an image magnetic monopole. Here we study the spectra of hydrogenlike ions near
the surface of a planar TI, taking into account the modifications which arise
due to the presence of the image monopole magnetic fields. In fact, the atom-TI
interaction provides additional contributions to the Casimir-Polder potential
while the ion-TI interaction modifies the energy shifts in the spectrum, which
now became distance dependent. We show that the hyperfine structure is
sensitive to the image magnetic monopole fields in states with nonzero angular
momentum, and that circular Rydberg ions can enhance the maximal energy shifts.
We discuss in detail the energy splitting of the $n$P$_{1/2}$ and $n$P$_{3/2}$
states in hydrogen. We also analyze the Casimir-Polder potential and find that
this magnetic interaction produces a large distance repulsive tail for some
particular atomic states. A sizable value of the maximum of the potential
requires TIs with very low values of the permittivity together with high values
of the topological magnetoelectric polarization.
