  New data from BESIII and LHCb show the existence of resonances with
strangeness filling multiplets of the broken SU(3)_f symmetry, with the pattern
predicted by the quark model. This is the case of the newly discovered Z_{cs}
(3985) and Z_{cs}(4003), which have a natural accommodation in the tetraquark
picture, as shown in this note. The quasi-degeneracy between Z_{cs} (3985) and
Z_{cs}(4003) reproduces, in the strange sector, the situation observed with
X(3872) and Z_c(3900). This represents a significative score in favor of the
tetraquark scheme.
