  In the general picture of high order theories of gravity, recently, the R^-1
theory has been analyzed in two different frameworks. In this letter a third
context is added, considering an explicit coupling between the R^-1 function of
the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion
of test particles which, in principle, could be connected with Dark Matter and
Pioneer anomaly problems.
