  If the equation of state of dark energy is anisotropic there will be
additional quadrupole anisotropy in the cosmic microwave background induced by
the time dependent anisotropic stress quantified in terms of $\Delta w$.
Assuming that the entire amplitude of the observed quadrupole is due to this
anisotropy, we conservatively impose a limit of $|\Delta w| < 2.1\times
10^{-4}$ for any value of $w\ge -1$ assuming that $\Omega_{\rm m}<0.5$. This is
considerably tighter than that which comes from SNe. Stronger limits, upto a
factor of 10, are possible for specific values of $\Omega_{\rm m}$ and $w$.
Since we assume this component is uncorrelated with the stochastic component
from inflation, we find that both the expectation value and the sample variance
are increased. There no improvement in the likelihood of an anomalously low
quadrupole as suggested by previous work on an elliptical universe.
