Endangered and Threatened Wildlife and Plants; Endangered Status for the Eastern Regal Fritillary, and Threatened Status With Section 4(d) Rule for the Western Regal Fritillary

We, the U.S. Fish and Wildlife Service (Service), propose to list the eastern regal fritillary (Argynnis idalia idalia) as an endangered species and to list the western regal fritillary (A. i. occidentalis) as a threatened species under the Endangered Species Act of 1973, as amended (Act). This determination also serves as our 12- month finding on a petition to list the regal fritillary, as these two subspecies make up the entire species. After a review of the best available scientific and commercial information, we find that listing both subspecies is warranted. Accordingly, we propose to list the eastern subspecies as endangered and the western subspecies as threatened with protective regulations issued under section 4(d) of the Act (a "4(d) rule"). We find that designation of critical habitat for both subspecies is not determinable at this time.