Cipher Pentominous

Rules: As in regular Pentominous, except that the clues are encrypted: lowercase letters are substituted for the uppercase letters that indicate pentomino shapes, with equal lowercase letters standing for equal uppercase letters and different lowercase letters standing for different uppercase ones. A lowercase letter that is a valid pentomino label does not necessarily stand for the corresponding uppercase letter – so that, say, a lowercase f may, or may not stand for an uppercase F.