Ah yes, referring to a female by a exclusively male title. That sure is good quality. (Pet-peeve no.2055)
In the Western World, women who hold titles of the their own right are always referred to by the feminine form of the title (with the sole exception of the Duke of Normandy — you can't change the order of succession of a polity which no longer exists). Men get the masculine forms as title holders, but never as spouses (thus the husband of a regnant queen is a prince consort).