Palos Verdes Blue Butterfly (Glaucopsyche lygdamus palosverdesensis)
4,300 (Estimated 300 wild and 4,000 captive).
Image: Joel Sartore/National Geographic. [larger view].
The Palos Verdes Blue butterfly is a small endangered butterfly native to the Palos Verdes Peninsula in southwest Los Angeles County, California. As its distribution has been proven to be limited to one single site it has one of the best claims to being the world's rarest butterfly.
Read more about the world's rarest butterfly.
Joel Sartore has shared some of his work on this blog before, so I am thrilled to tell you that National Geographic also appreciates his exemplary work. You can view more endangered animals of the United States that were photographed by the talented Joel Sartore here at National Geographic online. All images appear here by permission of National Geographic online.