  Phase singularities in quantum states play a significant role both in the
state properties and in the transition between the states. For instance, a
transition to two-dimensional superfluid state is governed by pairing of
vortices and, in turn, unpaired vortices can cause dissipations for particle
fluxes. Vortices and other phase defects can be revealed by characteristic
features in interference patterns produced by the quantum system. We present
dislocation-like phase singularities in interference patterns in a condensate
of indirect excitons measured by shift-interferometry. We show that the
observed dislocations in interference patterns are not associated with
conventional phase defects: neither with vortices, nor with polarization
vortices, nor with half-vortices, nor with skyrmions, nor with half-skyrmions.
We present the origin of these new phase singularities in condensate
interference patterns: the observed interference dislocations originate from
converging of the condensate matter waves propagating from different sources.
