The Collaborative International Dictionary of English v.0.48:

Qua \Qua\, conj. [L., abl. of qui who.]
   In so far as; in the capacity or character of; as.
   [1913 Webster]

         It is with Shelley's biographers qua biographers that
         we have to deal.                         --London
                                                  Spectator.
   [1913 Webster]