The executive director may, by regulation, and to the extent the executive director deems advisable, treat any species as an endangered species or threatened species even though it is not listed, if the executive director finds that:
(1) Such species so closely resembles in appearance, at the point in question, a species that has been listed pursuant to such section that enforcement personnel would have substantial difficulty in attempting to differentiate between the listed and unlisted species;
(2) The effect of this substantial difficulty is an additional threat to an endangered or threatened species; and
(3) Such treatment of an unlisted species will substantially facilitate the enforcement and further the policy of this part.