First, some basic information...
Subspecies of the old field mouse (Peromyscus polionotus). 8 of 16 ssp. known as beach mice.
Five Gulf Coast ssp., three Atlantic Coast ssp.
Three Gulf Coast ssp. listed as Endangered, one proposed for listing as Endangered.
Two extant Atlantic Coast ssp. listed as Threatened and Endangered, one ssp. extinct.
Most listed subspecific taxa (5 +1, federal). Second - grizzly bear and jaguarundi with 4 spp.