  In recent years, many heavy mesons and charmonia were observed which do not
fit in the conventional quark model expectations. Some of them are proposed to
be hadronic molecules. Here we investigate the consequences of heavy quark spin
symmetry on these heavy meson hadronic molecules. Heavy quark spin symmetry
enables us to predict new heavy meson molecules and provides us with a method
to test heavy meson molecule assumptions of some newly observed states. In
particular, we predict an \eta_c'f_0(980) bound state as the spin-doublet
partner of the Y(4660) proposed as a \psi'f_0(980) bound state with a mass of
4616^{+5}_{-6} MeV and the prominent decay mode \eta_c'\pi \pi. The width is
predicted to be \Gamma(\eta_c'\pi\pi)=60\pm30 MeV. The pi^+\pi^- invariant mass
spectrum and the line shape are calculated. We suggest to search for this state
in B^{\pm}-->\eta_c'K^{\pm}\pi^+\pi^-, whose branching fraction is expected to
be large.
