  We extend earlier studies of transverse Ward-Fradkin-Green-Takahashi
identities in QED, their usefulness to constrain the transverse fermion-boson
vertex and their importance for multiplicative renormalizability, to the
equivalent gauge identities in QCD. To this end, we consider transverse
Slavnov-Taylor identities that constrain the transverse quark-gluon vertex and
derive its eight associated scalar form factors. The complete vertex can be
expressed in terms of the quark's mass and wave-renormalization functions, the
ghost-dressing function, the quark-ghost scattering amplitude and a set of
eight form factors. The latter parametrize the hitherto unknown nonlocal tensor
structure in the transverse Slavnov-Taylor identity which arises from the
Fourier transform of a four-point function involving a Wilson line in
coordinate space. We determine the functional form of these eight form factors
with the constraints provided by the Bashir-Bermudez vertex and study the
effects of this novel vertex on the quark in the Dyson-Schwinger equation using
lattice QCD input for the gluon and ghost propagators. We observe significant
dynamical chiral symmetry breaking and a mass gap that leads to a constituent
mass of the order of 500 MeV for the light quarks. The flavor dependence of the
mass and wave-renormalization functions as well as their analytic behavior on
the complex momentum plane is studied and as an application we calculate the
quark condensate and the pion's weak decay constant in the chiral limit. Both
are in very good agreement with their reference values.
