The Lange's Metalmark butterfly was listed on the Federal Endangered Species List in 1976.

The Metalmark is a fragile, brightly colored butterfly in the Riodinidae (metalmark) family. Adult wingspan varies from 1 to 1.5 inch. Dorsal wings are largely black with white spots. Red-orange coloration extends through the inner forward half of the forewing, the hindwing bases, and a small central patch subtended by black. Below, the wings have a more muted pattern of gray, white, black, and orange. Lange’s metalmark butterfly was historically restricted to sand dunes along the southern bank of the Sacramento-San Joaquin River, and is currently found only at Antioch Sand Dunes in Contra Costa County.