  We consider the low energy implications including particle spectroscopy of
SO(10) inspired t-b-tau Yukawa coupling unification with mu < 0, where mu is
the coefficient of the bilinear Higgs mixing term of the minimal supersymmetric
standard model (MSSM). We imploy non-universal MSSM gaugino masses induced by
SO(10) invariant dimension five operators, such that the total number of
fundamental parameters is precisely the same as in Yukawa unified
supersymmetric SO(10) models with universal gaugino masses and mu > 0. We find
that t-b-tau Yukawa unification with mu < 0 is compatible with the current
experimental bounds, including the WMAP bound on neutralino dark matter and the
measured value of the muon anomalous magnetic moment. We present a variety of
benchmark points which include relatively light squarks (~ TeV) of the first
two families and an example in which the bottom and top squarks are lighter
than the gluino. This is quite distinct from Yukawa unification with mu > 0 and
universal gaugino masses in which the gluino is the lightest colored sparticle
and the sqaurks of the first two families have masses in the multi-TeV range.
