Abstract
The level staggering in π̃h92ν̃i132 two-quasiparticle bands in doubly odd Tl isotopes, for A198, is shown to be related to the signature dependence of the Coriolis interaction even in the presence of a proton-neutron residual interaction obtained from Bi208. The study of the neutron number dependence of this system suggests the existence of new isomeric states in very neutron deficient Tl isotopes and also reveals a possible inadequacy of the residual force or of the model itself.