  In semiconductors, the identification of doping atomic elements allowing to
encode a qubit within spin states is of intense interest for quantum
technologies. In transition metal dichalcogenides semiconductors, the strong
spin-orbit coupling produces locked spin-valley states with expected long
coherence time. Here we study the substitutional Bromine Br\textsubscript{Te}
dopant in 2H-MoTe$_2$. Electron spin resonance measurements show that this
dopant carries a spin with long-lived nanoseconds coherence time. Using
scanning tunneling spectroscopy, we find that the hydrogenic wavefunctions
associated with the dopant levels have characteristics spatial modulations that
result from their hybridization to the \textbf{Q}-valleys of the conduction
band. From a Fourier analysis of the conductance maps, we find that the
amplitude and phase of the Fourier components change with energy according to
the different irreducible representations of the impurity-site point-group
symmetry. These results demonstrate that a dopant can inherit the locked
spin-valley properties of the semiconductor and so exhibit long spin-coherence
time.
