  Very recently LHCb reported the evidence of a new charged charmonium-like
structure in the $J/\psi \pi^-$ invariant mass spectrum near 4600 MeV. In this
work we investigate this structure together with three other charged
charmonium-like states, the $Z_c(3900)$, $Z_c(4020)$, and $Z_c(4430)$. Our
results suggest that the two higher states can be established as the first
radial excitations of the two lower ones, all of which have the quantum numbers
$J^{PC}=1^{+-}$. We propose to search for more relationship among exotic
hadrons in order to better understand them.
