  We present a phenomenological constraint on a pseudovector light boson beyond
the Standard Model, which can induce a long-range spin-dependent interaction
$\alpha^{\prime\prime}({\bf s}_1\cdot{\bf s}_2)\,{\rm e}^{-\lambda r}/r$. In
the range of masses from $4\;{\rm keV}/c^2$ to those related to macroscopic
distances (of $\lambda^{-1}\sim1\;$cm) the spin-dependent coupling constant
$\alpha^{\prime\prime}$ of the electron-muon interaction is constrained at the
level below a part in $10^{15}$. The constraint is weakened while extending to
higher masses. The strongest constraint is related to the lepton-lepton
interaction. Constraints on spin-dependent interactions of some other particles
are also discussed. The results are obtained from data on the HFS interval of
the ground state in muonium and a few other light hydrogen-like atoms.
